Cris, a Digital Quest reader, seems to have messed up his Firefox about:config settings and would like to know if there is a way to reset it back to the default settings. Sure there is. Here’s how you can do it.
1. First, if Firefox is running, close down Firefox completely.
2. Now, start Firefox in the Safe Mode. For that, click Start, open the All Programs list, and navigate to the Mozilla Firefox folder. In the Mozilla Firefox folder, select Mozilla Firefox (Safe Mode). You can also start Firefox in Safe Mode by clicking Start, selecting Run (or use the Start Search box in Windows Vista) and then entering the following in the text field:
3. Firefox should start up with the following Firefox Safe Mode dialog.
Selecting any of the options and clicking on the Continue in Safe Mode button will be only temporary and the changes would last only for that session. Restarting Firefox in the normal mode will restore your extensions, themes, and settings will return to the state they were in before you entered Safe Mode. But that’s not what we are looking for right now.
4. To actually reset your about:config to default, in the above dialog, select the option: Reset all user preferences to Firefox defaults and, click on the Make Changes and Restart button. This will cause all changes you made to the about:config to be overwritten by the default values.
5. Now that your about:config is reset, you can start fiddling with it again!!
Suggested Reading: Backing up Firefox’s ‘about:config’ settings