Which devices are you hooking them into, and is it possible that they'd be sending a signal to the unit that would cause it to change inputs?
I have a Samsung HW-C450 soundbar. I noticed that it will randomly change from Digital 1 to Digital 2 when using it without anyone using the remote. I have returned one with the same problem and gotten another one with the same issue. I have hooked it up to different devices and it still does this. I am looking for any ideas as to why this happening