I picked up a midi file and am modifying it for backing tracks. The original bass line is on a electric bass. I did some copy and past with that bass line, adding a segment where the bass was not playing originally. Next I changed the instrument to acoustic bass. Now when I play back the cut and paste segment always reverts back to electric bass (although the instrument setting says acoustic bass). The rest of the bass line stays in the acoustic setting.
How do I get this segment to remain acoustic?

Thanks
Brian