Hi,
Please check if this happens in a new profile. If it's okay, you can later copy the needed personal data from the old profile. Firefox stores your personal data and settings in another location separate from its files/folder. A new profile would have the default Firefox settings (Tools (Alt + T) > Options, and about:config ), and usually would also be empty of any Extensions and themes (Appearance) in Tools > Add-ons) and their settings. Also, a new profile would have no previous stored website data/settings etc., (Tools > Clear Recent History).
Profiles Howto
Profile Folder & Files
about:config Entries
Hi,
Please check if this happens in a [https://support.mozilla.org/en-US/kb/Managing-profiles new profile]. If it's okay, you can later [https://support.mozilla.org/en-US/kb/Recovering%20important%20data%20from%20an%20old%20profile?s=profile&r=1&e=sph&as=s copy the needed personal data] from the old profile. Firefox stores your personal data and settings in another location separate from its [http://kb.mozillazine.org/Installation_directory files/folder]. A new profile would have the default Firefox settings ('''Tools''' ('''Alt''' + '''T''') > [https://support.mozilla.org/en-US/kb/Options%20window '''Options'''], and [http://kb.mozillazine.org/About:config about:config] ), and usually would also be empty of any '''Extensions''' and themes ('''Appearance''') in Tools > Add-ons) and their settings. Also, a new profile would have no previous stored website data/settings etc., ('''Tools''' > [https://support.mozilla.org/en-US/kb/Clear%20Recent%20History '''Clear Recent History''']).
[https://support.mozilla.org/en-US/kb/Profiles?s=profile&r=2&e=sph&as=s Profiles Howto]
[http://kb.mozillazine.org/Profile_folder_-_Firefox Profile Folder & Files]
[http://kb.mozillazine.org/About:config_entries about:config Entries]
