That's a feature that's been discussed ad nauseum. The easiest solution is to teach the command you need for the AV receiver to a device that only appears in that activity (DVD for dvd player, cable box for watch TV, etc. or just create a new device if necessary) and use that command for the LCD. It only propogates the changes to other activities that use the same device for the same purpose. So by using a device that isn't used in the other activities you can circumvent the feature.