# Using Firefox/Preferences
## Preferences

To access the Preferences window, navigate to Tools → Options on Windows, Edit → Preferences on Linux, or Firefox → Preferences on OS X.

### General

The General Tab of the Preferences window allows you to change a few things:
* Home Page
* Default Browser
* How Firefox connects to the Internet
The Home Page setting will most likely be the most used from this window, as the other two only need to be set once (if at all). There are four ways to set a home page from this window:
* Type an address into the Location(s): box (e.g., http://www.google.com)
* Select the Use Current Page(s) button, which will set the current page as the home page if only one is showing, or set all tabs as multiple home pages
* Select the Use Bookmark... button to open a dialog that will allow you to select a site currently bookmarked as the home page
* Select Use Blank Page to have about:blank set as the home page.
The first time Firefox is launched, it will check if it is set as the default browser. The option Firefox should check to see if it is the default browser when starting, when checked, will make sure that Firefox remains the default browser (or, if Firefox is not the default browser, it will ask you each time if you'd like it to be). Also, pressing Check now will do the check after the browser has already been started.
The Connection Settings button only needs to be used if you use a proxy to connect to the Internet. If so, you can have Firefox auto-detect the settings, manually enter them, or use an automatic proxy configuration URL.

### Privacy

The Privacy tab is described as follows: As you browse the web, Firefox keeps information about where you have been, what you have done etc. in the following areas: Each area has its own settings. As you select tabs inside the Privacy Tab, the main content area will change. However, there is one setting at the bottom of the window that is accessible from each tab. It says The Clear Private Data tool can be used to erase your private data using a keyboard shortcut or when Firefox closes. along with a Settings... button. Selecting that button will bring up a list of information that Firefox stores. Each can be set or unset individually. In addition to selecting which data you'd like cleared, there is an option to Clear private data when closing Firefox and another to Ask me before clearing private data. All private data that you have selected can be cleared at any time during a browsing session by hitting [Ctrl]+[Shift]+[Del].
Clearing private data is a public act that may, if your purpose was to keep some activity secret, expose that very secret. For a significant historical example see http://en.wikipedia.org/wiki/Soviet_atomic_bomb_project#Beginnings_of_the_program. Further, if "Clear Private Data" does not overwrite that data (and the prior paragraph does not so state) then that data may remain on your computer for some time and can possibly be accessed.

#### History

The History tab has only two items:
* Remember visited pages for the last __ day(s).
* A button to Clear Browsing History Now
These options are pretty self explanatory. Set the number of days you'd like Firefox to remember pages you have visited. Setting the value to 0 will cause Firefox to not use History. Pressing the Clear Browsing History Now button will erase all of the History.
The History is available from the Go → History menu item, by pressing [Ctrl]+[H], or by going to View → Sidebar → History. The Go menu itself also shows History.
History is an option for "Clear Private Data", and is selected by default.

#### Saved Forms

This tab, like the History tab, has only two items of interest:
* Save information I enter in forms and the Search Bar.
* Clear Saved Form Data Now
Checking the box (which is the default setting) will have Firefox save any data that is entered in a form. This includes things like the Google search box, any contact information (Name, Address, Email, etc) and other search boxes. Also, the Search Box included on the default Firefox toolbar (accessible by pressing [Ctrl]+[K]) Unchecking this box will stop Firefox from saving this information. Pressing the Clear Saved Form Data Now button will remove all the data currently stored by Firefox.
Saved Form Data is an option for "Clear Private Data", and is selected by default.
Note that you can clear out individual items (such as an erroneous or mis-typed entry) without having to clear all saved data. When the list of saved items shows up, navigate to the item you want to remove (don't click on it), then use the Shift-Delete key combination.

#### Passwords

When Remember Passwords is checked (default), Firefox will present you with an option to save a password on any site where one is entered. After entering a password and hitting the submit button, Firefox will present a dialog with three options, Remember, Never for This Site, and Not Now. Selecting Remember will have Firefox store the password for that page, and will automatically enter it on each successive visit. Selecting Never for This Site will prevent Firefox from remembering the password for that page, and it will not ask to save a password on that page again. Selecting Not Now will prevent Firefox from saving the password on that visit, but the dialog will be presented again the next time you visit that site.
Firefox also has the option to set a Master Password. Without one, Firefox will automatically enter any password that is stored--regardless of who is using the browser at that time. A Master Password will cause Firefox to prompt the user for a password before it will enter any saved passwords. However, it will only prompt once per session, meaning as long as the browser remains open. To prevent unauthorized use of passwords, be sure to close the browser when you are finished using it (if you entered a Master Password). The Master Password can also be unset from this window.
Pressing the View Saved Passwords button will open a new dialog. This window shows every site that Firefox has a username/password saved for. At first, the address of the site and the username are displayed. Press the Show Passwords button to display the saved passwords. Individual entries can be removed by selecting them, and pressing Remove. All entries can be removed with the Remove All button.
Also on the View Saved Passwords dialog is a tab that displays Passwords Never Saved. This window is very similar to the Passwords Saved window. Removing an entry from this list, however, will cause Firefox to ask to save a password the next time you visit that site.
Saved Passwords are an option for "Clear Private Data", but are not selected by default.

#### Download History

Any time you download an item from the Internet, Firefox opens the Download Manager to track it. After the download is finished, Firefox will keep that item visible. Each item can be removed individually, or the entire history can be cleared at once. Also, Firefox can be set to never save a history (or clear the download history on its own, after each download). The Download Manager can be accessed by going to Tools → Downloads, or by pressing [Ctrl]+[J]. It can also be accessed by pressing the View Download History button on this pane of the Preferences window.
The only setting here affects how Firefox clears the Download Manager. Remove files from the Download Manager:
* Upon successful download
* When Firefox exits
* Manually (default)
Upon successful download will erase entries from the Download Manager as they finish downloading, When Firefox exits will clear the Download Manager history each time Firefox is closed, and Manually will leave all entries in the Download Manager until they are removed by the user.
Note: Removing files from the Download Manager does not delete the files from your computer. It only removes the history of you downloading it from Firefox.
Download History is an option for "Clear Private Data", and is selected by default.

#### Cookies

Cookies are "pieces of information stored by sites on your computer. They are used to remember login information and other data." This window can be a little more confusing than the others.
The first option, which is enabled by default, is Allow sites to set Cookies. Next to that option is a button named Exceptions. Setting exceptions will allow cookies from every site except for sites on the list.
Under that are two more options:
* for the originating site only
* unless I have removed cookies set by the site
Checking the first box will only allow cookies that are from the site you are currently on. For other sites to give you cookies, you will have to navigate to that site (with the option enabled; it is disabled by default). The second option will except all cookies, as long as you have not removed a cookie from that site. For instance, if you remove a cookie set by google.com, then google.com will no longer be able to send you cookies.
Beneath those options is a dropdown box. Keep Cookies:
* until they expire (default)
* until I close Firefox
* ask me every time
Each cookie has an expiration date. By selecting the first option, Firefox will keep each cookie until it expires, and then discard it. Selecting the second option will keep all cookies only until Firefox is closed. The third option will make Firefox ask you each time a site tries to set a cookie, or modify an existing one.
Pressing the View Cookies button will bring up a new window, listing all cookies by site. From this window, it is possible to remove one, a few, or all cookies. Also, it is possible to view the contents of each cookie (though they are usually nonsensical).
Finally, the Clear Cookies Now button will clear all cookies.
Cookies are an option for "Clear Private Data", but are not selected by default.

#### Cache

Pages you view are stored in the cache for faster viewing later on. As you visit pages, Firefox will automatically save copies of them. If you navigate to the same page later, Firefox will use the page saved rather than downloading it again. With this setting, you can set the size of the cache.
Use up to __ MB of disk space for the cache. The default value is 50.
Press the "Clear Cache Now" button to remove all pages from the cache.
Cache is an option for "Clear Private Data", and is selected by default.

### Content

The first setting on this pane is for blocking popups. Firefox is set to automatically enable all unwanted popups. The setting is Block Popup Windows, and is enabled by default. To the right is an Allowed Sites button, that lets you set sites to accept popup windows from. When a popup is blocked, the yellow "information bar" appears at the top of the window. From there, you can allow the popup that was blocked, or allow access for the site to open popups. Sites can be removed from the Allowed Sites list, which will cause Firefox to block popups from that site again.
Next is the Warn me when web sites try to install extensions or themes. This is also enabled by default. To the right of that is an Exceptions button. Any site that is not on the Exceptions list (which contains only addons.mozilla.org and update.mozilla.org by default) will be blocked from installing extensions or themes. A yellow information bar will appear at the top of the window, very similar to the one that appears when a popup is blocked. If you want to install an extension or theme from the current site, you can add it to the exceptions list, and then retry the install. If the install was unwanted (e.g., a web site tried to install a malicious extension), you don't need to take any further action, as the install was already blocked. Do not add the site to your exceptions list unless you want to install an extension/theme.
Load images is the next preference. It is enabled by default. This preference also has an Exceptions list, though it works slightly different from the extensions/themes exceptions list. From this list, you can both allow and deny permission for sites to load images. For instance, if the Load images preference is enabled, you can use the Exceptions list to deny specific sites the ability to load images. If, for example, you did not want wikibooks.org to load images, you would type "wikibooks.org" in the Address of the web site box, and hit Deny. All other sites would be allowed to load images as normal.
If the Load images preference was disabled, then no images would be downloaded. However, if (again for example) you wanted wikibooks.org to be allowed to load images, then you would type "wikibooks.org" in the Address of the web site box, this time hitting Allow. All images would be blocked except images from wikibooks.org. Both types (allowed sites and denied sites) can be set at the same time, but would depend on the state of the Load images preference.
Below Load images is a preference (disabled by default) for the originating web site only. When enabled, images will only load if they come from the same site as the current page. However, this will not display images for such large sites as Yahoo! and Wikipedia, as images on those sites are stored on separate servers.
The preference Enable Java (enabled by default), controls whether or not Java applets are loaded in Firefox.
Enable JavaScript (enabled by default) controls whether or not JavaScript is executed by the browser. Pressing the Advanced... button will bring up a new window with the following options: Allow scripts to:
* Move or resize existing windows
* Raise or lower windows
* Disable or replace context menus
* Hide the status bar
* Change status bar text
The first three are enabled (meaning JavaScripts on a page will be able to do those actions) while the last two are disabled by default.
Finally, the Content tab contains Fonts & Colors settings. From this dialog, you can set the default font, and the default font size. The Advanced... dialog will allow you to select which specific fonts display which font type, and their sizes. The Colors... button allows you to set Link, Background, and Text colors.

### Tabs

The first Tab-related preference is "Open links from other applications in:"
* A new window
* A new tab in the most recent window
* The most recent tab/window
These options are mostly self explanatory. When another application (AOL Instant Messenger, for instance) tries to open a link, this preference will tell Firefox where to do it. The first two are easy enough to figure out, while the third will simply reuse the window that was most recently focused (replacing its contents).
The next preference is "Force links that open new windows to open in:"
* The same tab/window as the link
* A new tab
This preference is sometimes referred to as "Single Window Mode", as it prevents the "target:_blank" and "target:_new" attributes on links from opening new windows, always forcing Firefox to use one window. However, it has been disabled by default, as a few crashes have been reported with it enabled. There is little danger in enabling it, as it can be easily disabled again if a problem arises.
Three other preferences are on this window:
* Hide the tab bar when only one web site is open
* Select new tabs opened from links
* Warn when closing multiple tabs
The tab bar is hidden by default when only one website is opened. To have it always visible, uncheck the box next to the preference. "Select new tabs opened from links" can be described as "open a tab in the foreground". In other words, with this preference enabled (it's disabled by default), a new tab opened by middle clicking a link will automatically be selected and visible. The default behavior is to have the new tab open in the background, where you have to manually select it to view it. The final preference is visible by opening more than one tab and trying to close the window. A warning will be displayed to make sure all of the tabs can be closed.
It is also possible to extend tabbed browsing functionality through Firefox's extension system. See Chapter 6 for more details on extensions. If Firefox split windows in taskbar when group tabs "browser.taskbar.previews.enable" to "FALSE" in about:config

### Downloads

The Downloads tab has several preferences. First, there is the option of setting a "Download Folder". If Ask me where to save every file is selected, then Firefox will prompt you for a location to save every file you download. Selecting Save all files to this folder: will make it so every download goes to the same location. The Desktop is the default location for downloads on Windows.
Next, Show Download Manager when a download begins, which is enabled by default. This brings up the download manager for each file that is downloaded. You will manually have to close the Download Manager unless the preference Close the Download Manager when all downloads are complete is selected.
The final preference states Firefox can automatically download or open files of certain types. Pressing the View & Edit Actions... button will bring up a new window. It contains a list of file extensions, and default actions for files of that type. Each file type can be set to automatically open with its default application, automatically open with a non-default application, saved to the computer, or opened with a plugin (assuming the correct plugin is installed). At this time, there appears to be no "Add" button, so you're out of luck if the type you want to handle is missing from the list. Additionally, some users may have a blank dialog box (as of 8-8-2006), in which case none of the extensions are listed. The issue is mentioned at http://forums.mozillazine.org/viewtopic.php?p=2400536&sid=d02c030728278592cbeb3aee9805b14b but the fixes described may not work for all users. Those users should locate their profiles folder (%AppData%\Mozilla\Firefox\Profiles\xxxxxxxx.default on WinXP where x is a random character), and delete the appropriate files there.

### Advanced

This pane offers some advanced settings. There is a third tab offered under "Advanced", "Security". However, most users should not need to change any preferences on this tab.

#### General

The setting Allow text to be selected with the keyboard controls caret browsing. When using caret browsing, a cursor is placed in the browser, and it can be moved with the arrow keys and used to select text. Pressing [F7] will also enable and disable this feature.
Begin finding when you begin typing is a setting for Find As You Type (FAYT). Normally, FAYT is activated only after pressing the / or ' keys, or by pressing [F3]. With this setting enabled, FAYT will begin when any key is pressed (as long as the cursor is not in a form, or other text entry area).
Resize large images to fit in the browser window will automatically resize any image that is larger than the current browser window so that it fits in the window without causing scrollbars. Clicking on the image will display it at its full size, and clicking on it again will resize it to fit the window.
Use autoscrolling toggles the ability to autoscroll. With autoscroll enabled, click the middle mouse button to enter autoscroll mode. While in autoscroll mode, simply move the mouse up to scroll up, and move the mouse down to scroll down. Clicking the middle mouse button again will exit autoscroll.
Use smooth scrolling toggles the ability to make scrolling with the mouse wheel "smoother" than normal.
Finally, click the Edit Languages... button to change the order of preference of languages for pages that offer more than one language.

#### Update

The Update tab changes the way Firefox checks for updates for itself, extensions and themes, and search engines. All three should remain checked, as critical security updates will use the Update system.
The final preference determines how to install updates. If Ask me what I want to do is selected, then Firefox will alert you when new updates are found and wait for instructions. If Automatically download and install the update is selected, Firefox will apply updates without asking. However, if Warn me if this will disable extensions or themes is checked, and a new update may break a currently installed extension or theme, Firefox will display a warning.
Finally, select the Show Update History button to see a list of previously installed updates, and what they contained.

### Multiple Users

With Firefox, it is possible to create many different profiles each with its own settings. This has several advantages, because it allows you to install the extensions you need for web development, while not slowing down your browser for normal surfing. The disadvantage is that only one profile can be running a the same time. To switch profiles, or add new profiles, you need to run firefox -profilemanager. On Windows, this can be achieved by typing the command into the "Run" dialog on the start menu, on most other systems this can be run wherever a command may be run, usually a Terminal or Command Line.
This command must be run when firefox is not running on your computer, if it is running,you will just get a new window with the preferences for the currently active profile. The dialog box that opens when the command is run successfully allows you to select from a list of profiles. With each profile you have the option to either "Rename" or "Delete" it, or just to "Start Firefox" by using it.
When you delete a profile from the profile manager, it asks you whether you want to delete or keep the files that contain the information associated with it. If you select the delete files option, then all private data associated with that profile, including history, saved passwords, and cookies, are deleted from the hard drive. There is no reason to keep these files as creating a new profile under the same name as the deleted one will not restore the profile.