I have a strobe sensitivity and visual motion sensitivity, so the default Firefox settings aren't safe for me. (For example, the default settings have flashingcursors, autoscroll, smooth scrolling, autoplay enabled, no ad blocker installed, etc.) I can't use a new profile unless I can copy over all my existing safety and accessibility fixes. Besides about:preferences, that includes a number of fixes to about:config, userChrome.css, userContent.css, and a number of add-ons. I am not quite sure what the Autoconfig can do, or how to set it up, but I understand I would need to manually track down and copy all my safety settings, which isn't even possible with the current about:config. And wasn't practical with the old one. Anyway, trying to follow debugging instructions, which often involve creating new profiles, and then copying everything to these profiles so I can test them relatively safely, has gradually screwed up my Firefox installation. A lot of freezes, the url bar going unresponsive, etc. Maybe if I can sync to a dummy location and then back I can fix this. I don't know what else I can do.