@Yonder Hi

For God Knows which reason, retroarch defined buttons like :
1 -> B
2 -> Y
3 -> A
4 -> X

Which is totally illogical with their idea of A to validate and B to cancel (thus making it work with any pad).

BUT : you can use the "core remap" feature : buttons will be remapped according to how you set them up. You do it once for all for every 8bit core