The length of the Tab character is inconsistent so you shouldn't rely on it for margins. Such documents contain special information for formatting it. So, when you make a character bold, the file saves that information.
Characters are usually proportional width.
You have to manually format it. Nothing fancy, just plain and simple. Mode Copy your entire resume and then paste it into a text editor. Both Macintosh and Windows machines have an editor called Notepad. Make sure you save the file as Plain Text .