The thing that absolutely pisses me off is how I try to be actively aware of what settings I disagree with and disable things I don't like - and then an unseen update resets things to default.

HOW MANY TIMES MUST I UNCHECK WHAT TO SYNC TO MY ACCOUNT? YOU WOULD THINK THAT IS SAVED PERSISTENTLY.

I think my qualify of life on Firefox would be improved greatly if a notice popped up saying some of my settings were reset to defaults because of breaking changes (or minor). Like they give a crap.