You purposely want to build a cab that can not play most games? 😯
Anyways you'll have to check the keys n the mame menu, i think by default you access that by holding start. you can also open it from the retroarch menu, you can not see it from within emulationstation like you're trying to do on the picture.
Start the game first.
copy the default RA-controller-config to another place of your choice (i.e.: "/home/AMIBERRY Inputs/")
edit the button-mapping as you like in this copied file
go to "paths", navigate the "inputs"-path to your new one.
click on the button "rescan paths"
There you go, the inputs are now as you like to have them global for all games ;)
Sorry, but you're using a 3rd party image bundled with the hardware, which we don't/can't support.
Note that selling RetroPie is against the project's license - https://retropie.org.uk/about/legal/, so you've been scammed, since RetroPie is free/open source software.
@ooskay I am away from my setup, and I don't even know where a config lives for GPIOnext. You might ask questions about GPIOnext on the github repo. The developer has been very friendly and helpful users in the past.
If you want to go the stripped down route, you can find examples of raw python scripts that setup GPIO pins for input all over the internet. In my opinion, the key to making a script successful is to define OS commands as a function that gets called when the GPIO pin is triggered using EDGE detection method. The script ends in a Pause loop or a while loop so it never terminates.
Then, you just need to launch the scrip at startup. Sorry to be so abstract about it, but it was definitely a learning process and everyone has a different config than you.
I'm using a Pac-Drive from Ultimarc for my LED buttons. @savetheclocktowr made a controller software for some nice sequencing effects. It's not needed for permanent lighting, the Pac-Drive will do that out-of-the-box in Retropie.