"Look at Edge: I wanted to save a PDF I was viewing. Fat chance."

Relevant: I had to quit using Firefox though, because of the brain-dead bookmarks being buried several levels deep in menus, and worse in the mobile version.

Enable the menu bar in Firefox - given this thread, that'll probably be a great joy for you. I love the menu bar, it's so convenient.

Thanks. I particularly hated the burying of bookmarks on mobile, so is there a way to address that?

You mean how it defaults to a different folder? Yeah, no idea on that one. Mozilla needs to give bookmarks some love imo, but I think far fewer people use them than one might expect.