GPO policies can also be stored in HKEY_CURRENT_USER and in a policies.json file in the distribution folder in the Firefox program folder. *https://github.com/mozilla/policy-templates/#disableappupdate You can inspect the Mozilla and Firefox keys with the Windows Registry Editor in HKEY_LOCAL_MACHINE and in HKEY_CURRENT_USER with the Windows Registry Editor to see whether GPO policy rules are active. *HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Mozilla\Firefox\ *HKEY_CURRENT_USER\SOFTWARE\Policies\Mozilla\Firefox\