A procedure to get (e)ARC to work on a 2020 QLED 80T TV and Yamaha (Dolby Atmos) A/V Receiver
So I was having a really hard time getting ARC to work with my 2020 55" QN80T QLED TV and my Yamaha receiver. (I especially wanted to see if I could get Dolby Atmos sound using the "Netflix" app on the TV.) I tried doing this today and it got the ARC functionality working, at least. If you're having a similar problem of getting ARC to work on your QLED TV with your Dolby Atmos A/V receiver, you can try this:
1) Go into the QLED TV's settings. 2) Go to General>External Device Manager.
3) Turn on "Anynet+ (HDMI-CEC).
4) Exit from that menu.
5) Go to the Sound>Expert Settings menu.
6) Select "HDMI-eARC Mode." 7) Select "Auto." 8) If your external device (i.e., your A/V receiver is Dolby-capable, turn on "Dolby Atmos compatibility.")
On my Yamaha receiver (this may not be the same for all receivers, so look for an equivalent function on your receiver) I did the following:
1) Go to your "HDMI Controls."
2) Turn on "HDMI Control."
3) (Wherever it may be on your receivers menus) Turn on "ARC." 4) Set the "TV audio input" to "Audio1".
This worked for me. No guarantee that it will work for you, but give it a try.