Two questions about Batocera Linux

I have this installed on a PC, and I have a couple of issues. The audio is messed up, as in, it comes out glitchy and popping all over the place, it’s not pleasant to hear. Also, I’d like to use Retroarch as the default front-end, anyway to change that? Where is it located by the way? I can only launch it via the config shortcut in the apps menu in the file explorer, but that defaults to rgui menu driver all the time and it’s kind of annoying. Any ideas? Thanks.