XP-50 saving sounds

[ATF]

If you change a few instruments or drum sounds in the XP-50, how can you save it so when you load the song they come back up?

Thanks

[Universal Exports]

I take it you're using the sequencer as well as pulling up a performance memory for each song? All sixteen slots in a performance are editable with drums being reserved for channel 10. Whatever edits you make to each instument patch can be saved and then re-written to the performance. Do you have access to the owner's manual?