do you get link menu sounds?

when you stream to other devices do they get sound
try link apps for pc/mobile/linux etc..

if menu sounds work, but no sound from host
check windows mixer volume on host pc, make sure steam client/bootstrapper volume is maxed

I'm not so sure about the Steam Deck, but assuming menus are more or less the same for the Steam.
Just the way you phrased it "external device" doesn't seem right to me, so I think that perhaps you are not using the right option.

My suggestion is as follows,
On your STEAM DECK, you should try to go to [Steam]> Settings > Remote play
On Remote play tab, scroll down until you see "Advanced Streaming Options", toggle that on (until blue). A list of options should become available right below.
The first one should be "Play audio on host". Toggle that off (until gray). Hopefully this solves it.

Also, a bit below there's "Enable Advanced Client Options".
If you toggle that on, another list of options are available and there you can edit how you want your stream to look like. Instead of editing directly on your Steam Link Client at your TV, maybe try that method instead since you seem to be having issues with options memory.

This is Steam Link discussion.

Originally posted by udidwht:

This is Steam Link discussion.

Steam deck uses the Steam Link App to connect wirelessly to other devices.
Even though there is a specific discussion page for Steam Decks, it's not totally wrong to come here either.

Originally posted by Naguisaua:

Originally posted by udidwht:

This is Steam Link discussion.

Steam deck uses the Steam Link App to connect wirelessly to other devices.
Even though there is a specific discussion page for Steam Decks, it's not totally wrong to come here either.

OP makes no mention of either.

deck to tv, deck is host

steam link hardware and apps are for client