Hello Take a look at https://connect.mozilla.org/t5/discussions/here-s-what-we-re-working-on-in-firefox/m-p/57877/highlight/true#M20366 Take a look at https://forums.mozillazine.org/viewtopic.php?p=14960439#p14960439

Thanks Agent virtuel, I have marked this thread as resolved.

This is an old mozillaZine KB article http://kb.mozillazine.org/About:config_entries that has not been updated since 2017. Many of the Preferences have since been made obsolete or had changes in Value and such. It was a challenge to keep it updated and there were idiots that kept trying to modify the article as if they were editing their own about:config on some certain preferences. The problem with trying to keep such a list updated is that many Preferences can be temporary for one version or a version range. There are also hidden preferences and a few are even ones where modifying the value has no effect. An example of a Preference you cannot modify is the old obsolete front-end preference app.update.channel still listed in about:config as all it does is show what channel you are on. You have to change the channel with channel-prefs.js though installing the Firefox version from the channel you want is easy to do. https://support.mozilla.org/en-US/kb/about-config-editor-firefox <blockquote>'''Warning:''' Changing advanced preferences can affect Firefox's stability and security. This is recommended for '''advanced users only'''.</blockquote>