Apple TV Volume control

Hello All,
I have managed to successfully set up the Apple TV and Onkyo receiver but Im having one issue controlling the volume of the Apple TV when I connect my AirPods.
I can control the volume of the Onkyo received but once the AirPods are connected I’m un able to adjust the volume of the Apple TV to adjust the volume in the AirPods.
I have tried setting the Channel up and Channel down hard buttons to control the volume of the Apple TV but this doesn’t make any difference.
Has any one else managed to make this work?
Thanks