You need to create a new profile with the stable release. How to create a new profile. https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switc

You need to create a new profile with the stable release. How to create a new profile. https://support.mozilla.org/en-US/kb/profile-manager-create-remove-switch-firefox-profiles https://support.mozilla.org/en-US/kb/profile-manager-create-... Install the stable version but don't run it yet. Then follow the instructions to start the Profile Manager when Firefox is closed. If you need to recover data from your old profile, the link above has instructions too.