Hi, if fonts changed and do not revert back when you restart Firefox it will be in your Profile I would think so A reinstall will not do anything. Under Options --> General --> Language and Appearance default should be should say Default (Times New Roman). Is this not listed in there ? Please Backup as you wished to do : *https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles *https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer Did anything unusual happen or install something, crash ? Please try in : SAFE MODE *https://support.mozilla.org/kb/Safe+Mode *https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes In Firefox Safe mode these changes are effective: *all extensions are disabled (about:addons) *default theme is used (no persona) *userChrome.css and userContent.css are ignored (chrome folder) *default toolbar layout is used (file: localstore-safe.rdf) *Javascript JIT compilers are disabled (prefs: javascript.options.*jit) *hardware acceleration is disabled (Options > Performance > Uncheck to view) *plugins are not affected *preferences are not affected TEST'''''''''is issue still there ?

Can you attach a screenshot? *https://support.mozilla.org/en-US/kb/how-do-i-create-screenshot-my-problem *use a compressed image type like PNG or JPG to save the screenshot