I have a TCL A8 TV and a Corsair hs70 headphone, when I plug the USB dongle to the TV the android part of the tv(YouTube, Netflix, etc), and the menu sound come from the headphone no problem, but when I switch to HDMI source(PC and Switch) the audio output through the speaker. Can I change something so when I plugged the headphone the audio for HDMI source come from the headphone? I fiddle with the setting but there's no option to change audio output.
The USB is probably only exposed to the Android side as you have noticed. Most likely there is nothing to route the other outputs to that.