I am pretty sure I followed your directions correctly, of maybe not noob after all. I tried messing with it a little last night and scrolling through the nes emulator all the games where mapped the same way now. Not sure what I did however. I followed that one reddit post about adjust the keys within the game itself and to safe that config to change “/opt/retropie/config/nes” But I always get permission denied. Tried things to get around that but no luck on changing the retroarch.cfg file. But some how all the nes roms work

Tried to recreat one snes nothing can change in game safe copy down the file name. Exit, reenter the rom and nothing is saved. Go to the command line and try same issue permission denied