First step is to quickly find out if this is potentiometer "jitter" related or if it's further on the mainboard.

The way to test for pot jitter is to power off the amp, then turn ALL knobs to either absolute left or absolute right-most positions, physically on the panel. The idea here is that when the knobs are parked at the extremes, they are physically less subjected to vibration of the amp.

If you've done this, then gently "wake" the Channel Volume knob and the channels still appear to "switch by itself", the issue is deeper on the DSP mainboard and would definitely require a service technician to access the mainboard components for diagnosis and correction.