@David-CM
It has always been the case that when you put a YouView box onto Surround sound, the volume on the box goes to maximum and stays there, and everything else you have observed comes from that.
As to why YouView do that, I don’t know, and they have never said; but I would imagine that they found volume-reduced surround sound compromised in some way.
It’s also true that if you select surround sound, you are implying that the sound will be passed through the TV to some sort of surround system (otherwise what’s the point?) and you will want to be controlling the volume there, via the TV, rather than on the YouView box.
See the note to this effect on Settings/Picture & Sound. Though when this note warns that it will disable volume controls on the remote, it didn’t envisage that this would now only be true for Set Top Box in Settings/Bluetooth Remote/Control Volume and Source, and not for TV, when you have your remote programmed to control the TV.
And so, if you choose surround sound, and you want the YouView remote to control the volume, you need to select that it controls the TV, rather than the Set Top Box, in Settings/Bluetooth Remote/Control Volume and Source.
It’s a pity these settings don’t toggle together; but that’s probably because the Box can’t absolutely rely on the remote being able to control the TV, or whatever else might be controlling the audio volume here.
*Longtime YouView box owner & broadband customer (was BT now EE), but only recently a full EETV subscriber*
