Reply To: Confused beginner here, many questions

[Floob]

Are you sure your 0.37b5 romsets are correct?
You can verify that by using the dat files on this page:
https://github.com/retropie/RetroPie-Setup/wiki/Managing-ROMs

In RetroPie 3, those roms should go here:
/home/pi/RetroPie/roms/mame-mame4all

As the game starts to boot, you should get the option to press “x” this lets you choose if you want to run it with mame4all-pi or Mame-libretro. I tend to use mame4all-pi.

More details here:

MAME versions and romsets on RetroPie