I'm similar. I happily used Firefox without caring for years, then one day I fire it up and think "What the fuck is this? Has it been replaced with Chrome suddenly?". I try to customise it back to how I liked it, only Mozilla know better and have removed most the customisation options.

A quick Google later and I stumbled upon Pale Moon. Quickly installed it, and back to how I like it.

I'm not a geek that messes around much. I only use a few addons, but it irks me when they randomly change things for no good reason, and remove functionality at the same time.