Volume control for HD versus SD channels

[notbear]

Hi there. I recently upgraded to a 4K TV, and changed some favourite channels on my T3 to be the HD versions to get a better picture. My T3 is connected to an AV receiver, then to the TV via HDMI ARC.

However, the volume on the HD channels can only be controlled by the TV or receiver remotes, with the SD channels still able to use the Beyonwiz remote. Is there some audio or passthrough settings I can configure to use the one volume control? I was trying the downmix to stereo settings without success. The volume is also different between HD and SD, and adjusting it all the time and switching is annoying.

Btw, I did configure the Beyonwiz remote for the new TV buttons (so much trial and error!), but you can probably appreciate other family members not being conducive to having to switch between the two, and having to adjust the volume all the time when channel changing. TIA.