If you're using just Mame you can alter the keystrokes in the tab menu. That may have prevented your first program, too. But the combos you mentioned are included in the ctrlr (and also perhaps in your ctr file if you cut and pasted it there) file in Mame. If you open it you will see them written somewhere. You can probably revise it right there by changing "player one" to whatever you want and "left paddle" to whatever you want. I would urge you to make a backup of the file, because I'm a bit unfamiliar with it and I wouldn't want you to be stuck on my advice. Please ask if you need more help. Also, do you have X-arcade version 1 or 2? If you just bought it, it;s likely 2.