Some channels have surround sound (5.1, 7.1, Dolby). Many TV boxes cannot decode it, so the app passes the sound to your TV or receiver as it is, and the TV decodes it. The side effect: the box no longer controls the volume of this sound, and only the TV remote does.
Switch codec, and choose Use software audio decoder.
The channel restarts and the app remembers the choice. (The item is there while the channel plays with
Use hardware codecs.)Settings > Player > Setup codecs preferences > Use software audio decoder, or the same switch
in Media tracks of the player menu.The box then decodes the sound itself, so the volume works as usual.
Playing the channel with Use software VLC has the same effect (see
Choosing a codec).
Settings > Player > Manual audio volume fine-tune (limited by system volume) (premium, hidden in Simplified mode):
the volume slider of the player then sets the app’s own volume, from 0 to 100% of the device volume, instead of the
volume of the whole device. Use it when the device volume steps are too coarse, or to make the app quieter than other
apps. It cannot make the sound louder than the device volume.