pref("general.config.filename", "mozilla.cfg");
pref("general.config.obscure_value", 0); // use this to disable the byte-shift

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

You can use a mozilla.cfg file in the Firefox program folder to lock prefs or specify new (default) values. Place a file local-settings.js in the defaults\pref folder where you also find the file channel-prefs.js to specify using mozilla.cfg. pref("general.config.filename", "mozilla.cfg"); pref("general.config.obscure_value", 0); // use this to disable the byte-shift See: *http://kb.mozillazine.org/Locking_preferences 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 ---- *http://mike.kaply.com/2012/03/16/customizing-firefox-autoconfig-files/ *http://mike.kaply.com/2012/03/22/customizing-firefox-advanced-autoconfig-files/