@sroach See if one of these links helps you:
https://recalbox.gitbook.io/tutorials/v/francais/configuration-des-boutons-personnalises-1/comment-personnaliser-mapping-manette https://recalbox.gitbook.io/tutorials/v/francais/configuration-des-boutons-personnalises-1/creer-une-configuration-custom-par-emulateur https://recalbox.gitbook.io/documentation/v/francais/utilisateur-avance/configurations/surcharge-de-configuration