4 usb controller mapping

[Petemu]

Have a moded arcade 1up system with 4 usb controllers and buttons. These controllers show up in mame fine and also seem to work RetroX but there does not seem to be a way to change the game pad settings for each individual controller. I can set up my player one controller which works fine in mame but other controllers seem to not have all of their buttons mapped. Is there any way to individually map these buttons. I do see a on screen popup happen when I click on button from each user so I know they controllers are being recognized