John,
In answer to your original question, as many have mentioned, the Help => About... => Session is the most reliable way to quickly find out where the user's preferences file is located. Once you find it, you can modfiy it with a text editor. However, the easiest way to "reset" the user's environment is to simply delete the file. Arbortext will automatically build a new one based on the defaults. Once you have an operational Editor for the user, you can go to Tools => Preferences and click on the Advanced button to individually set values that you may have unique for your installation.
On a side note, if you care to control that file, you can, through an ENV variable, control it's location. This would include putting it on a server where all users could point to. Then, through access rights, control the modifying of the file. That way, all users start with a known point. They all can modify their settings once Editor is started, but they wouldn't be able to save them. Good control for consistency.
HTH,
Bob