Here I see what you did but it's not supported (the secret menu.)
However there are issues with the YouTube app such as it's been discontinued much to everyone's dismay. But about NETFLIX. I often have to look around the menus in Netflix to change the audio output to optical and often have to select the Stereo or PCM audio track. THIS is not documented in a web page so I have to stop here. But it's what I've found works for most of the time.
samsung tv 55MU7000 doesn't have builtin option for Bluetooth headphones so i searched online and found out that from secret menu you can turn that on but after doing step by step it did add an extra option in sound output menu "buletooth speaker" instead bluetooth headphone. after that i purchased digital to analog converter and bluetooth dongle. this is how i did it; connected converter with tv via toslink cable and on output side of converter attached audio cable (red and white) and on the other side of that cable attached bluetooth dongle. later connected my headphones with it and successfully got voice in my headphones. now problem is i can listen cable TV on my headphones but when i shift to youtube or netflix i hear loud noise in headphones.
can anyone help me out here TIA?

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