I opened a midi file in powertracks and changed the instrument patch, but every time I restart the file it reverts back to the original instrument. how do I stop this from happening? i tried changing the channel and even copy and pasted in a new track. It still changes back every time I restart.

If its a midi file you downloaded from the internet, its probably got the instrument hard coded into the file. Unless you change that it will keep happening. Go into the Event List and delete the Program Change event at the beginning of the offending track.

Jeff