If you want to switch the volume control to the HDDTA, press and hold the setup button until the LED blinks twice and then press and hold the mute button until the LED blinks twice again. This is helpful if the customer has in issue with the volume not going very loud on an HDDTA. Turn the volume on the box all the way up. Then switch the volume control back to the TV by pressing and holding the setup button until the LED blinks twice and then press and hold the volume + button. You should be controlling the TV volume.