Volume control when connected to TV

The volume controls on my Liberty Air 2’s work fine when connected to my iPhone. However, when connected to my Smart TV, I am unable to adjust the sound making the them unusable.

Can you control the sound by the tv?

No, the TV is down to zero.

I would also have expected volume control to be via the TV in this situation. If the two volumes aren’t linked, I would have to reach out to support.