Search on YouTube, easy hax background music. I am using his work, very simple script he made for background music.

i have solved it now thanks , there is a button in retropie menu to disable it, the image was motion blue + attract mode. all the music fades out before the emulators loads, apart from daphne and c64. like they have not been added to the music script or something. thanks for your reply

I think that someone might need to make a new variable called background music
because the only other one that could work is scroll sound or you could make it that when you enter the desired emulator it will play a music through where the snap would play, I am not sure if that works though but I better just start experimenting :)