You can password protect your settings and other Firefox features using the Public Fox add-on.

Please keep in mind though that this add-on can be disabled by entering Firefox in Safe Mode. If the other users do not know how to do this, the add-on should work well.

You can use a different Windows account to prevent other users from changing settings in your Firefox profile folder.

You can use a mozilla.cfg file in the Firefox program folder to lock prefs or specify new (default) values.

Place a local-settings.js file in the defaults\pref folder where also the channel-prefs.js file is located to specify using mozilla.cfg.

pref("general.config.filename", "mozilla.cfg");

These functions can be used in the mozilla.cfg file:

defaultPref();  // set new default value
pref();         // set pref, but allow changes in current session
lockPref();     // lock pref, disallow changes

See:

• http://kb.mozillazine.org/Locking_preferences
• http://mike.kaply.com/2012/03/16/customizing-firefox-autoconfig-files/

Note that this will affect all Firefox profiles that are started with the Firefox installation that uses this program folder with the mozilla.cfg file, so you may have to do a custom install and install Firefox a second time in another program folder.