Easy MAME QOL by Key Mapping e.g. Gradius

How to easily re-map buttons when playing MAME.
I re-map for Gradius in this example.
NOTE: To reset a mapping, long-press A instead of tap A.
[ Usually , press A to select 'key' then press the button you want to asign; but to reset to default, long-press A to reset that button to its Default.]

[@shawnferguson5121]

Had this prob on vulcan venture about an hour ago
Gonna change like you showed
Thanks

[@shawnferguson5121]

Do you have to save or is it automatic?

[@toms-cubes-and-games]

I made a mistake.
It doesn't seem to save automatically at all!
Weird, it saved it on my rg351p and I assumed it would here too but it doesn't!
Will look into this in 2024!