Forum pomocy dla programu Firefox

Every time I sign onto Firefox I get the attached message. I think that uninstalling Firefox and reinstalling "may" resolve the problem, but Firefox won't uninstall. I have tried four different ways and it won't uninstall. Can you help me an uninstall process?

I have been using Firefox on my Mac for years with no problems. Recently, however, I have been having trouble running YouTube. I get to the correct page for the video I want but the video itself does not show up, just the background for the page. Any idea what I might have done to create this problem?

So for some reason I have two versions of Firefox on my computer (Windows 64 bit), I am logged in and using one of them, and the other is just there. I could log in there but I don't want to, I just want to get rid of it. Links from Telegram open in it, creating a second Firefox window instead of opening in another tab in the already open Firefox window, which is very inconvenient. The windows list of programs which can be uninstalled only has one Firefox (I've tried deleting and reinstalling, it doesn't help). But when I try to choose a default browser I get 2 icons to choose from which look the same (see screenshot). What the heck? How do I manage this!