unfortunately rtfm isn't clear enough for some people sirp 
Also unfortunately the default mame setting have about six things that are WRONG for basically all users.
The biggest ones are.
Defaulting to the OK screens.
Defaulting to mouse not working.
Defaulting to joystick not working.
I can understand the motivations behind the OK screens, but turning off mouse and joystick input by default is just stupid. A default configuration that must be changed by almost all users is obviously set wrong.
A hardware equivalent would be if your motherboard defaulted to turning off the onboard floppy controller and the secondary IDE channel, because you might not have anything hooked up there. Almost everyone does, but hey, YOU might be the exception, so set it up for the exception instead of the rule.