1. Go to Menu > Preferences > MIDI / Sync tab, and ensure that the TRACK buttons are enabled for the Output Ports corresponding to MPC A and MPC B.
2. Press the Main button, tap + New Track, then tap MIDI.
3. Long press the title of the MIDI track to bring up the Track Settings menu.
4. Check the Program Change box and set a value under the MIDI PROGRAM CHANGE drop down menu.
The track will now send this value when played.