Just installed firefox 71. The about:preferences#privacy section appears missing, the back button and address bar cannot be operated except via drop menus. Fix?

Try the Firefox version from the official Mozilla server if you currently use a version from the repositories of your Linux distribution. *https://www.mozilla.org/en-US/firefox/all/ You can create a new profile to test if your current profile is causing the problem. See "Creating a profile": *https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles If the new profile works then you can transfer files from a previously used profile to the new profile, but be cautious not to copy corrupted files to avoid carrying over problems. *https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile