I never had any of these issues before I had signed into a Firefox account and as stupid as it sounds, I kinda ''accidentally'' signed into my Firefox account with intending to, I had just downloaded Firefox on my laptop and wanted to sync my other devices with my home PC. But ever since I logged onto said account, it has just acted strangely. Never saves sessions even though when I look back at previous history, it remembers all the tabs and sites I've had opened. And it also entirely forgets my YouTube settings, never putting it in Theater Mode from the start like it used to. Hope somebody has some answers or something, it's been over a week like this and nothing has helped so far.