It depends on whether Bing was set as the default search engine with or without your consent. If the tweak doesn’t stem from an informed decision on your end, then you are dealing with a virus that bypassed regular authorization when putting the unwanted changes into effect. In case this isn’t a malware issue, simply go to your browser’s preferences, proceed to the search settings, and pick the right search provider on the list. For instance, in Safari you need to open the Preferences screen, then click the Search tab, and opt for Google in the ‘Search engine’ area. This way, Bing will be automatically deselected. The procedure is similar for the other popular web browsers. The fix isn’t nearly as easy if malicious code is involved. The Bing redirect virus will prevent you from changing the default search engine via the commonplace technique. The search providers may be grayed out and not clickable. In this scenario, you’ll need to remove the harmful app before reverting to Google manually. Try to turn off all the extensions in the malfunctioning browser for a start. If this doesn’t do the trick, follow the virus cleanup walkthrough in the article above.