Hi @amnett 

Obviously you’re not in the US judging from the language showing in your picture.  I’m going to take a wild guess an assume the Stue refers to your Beam   If so select it and not Apple TV.  Let me know if I guessed correctly 

Also, assuming this is a 4K version of Apple TV, go to Settings > Video and Audio > Audio Format and make sure it say Dolby Digital 5.1. If it doesn’t, select it, then select Change Format, and select Dolby Digital 5.1. 

Hello @AjTrek1 . Thanks for answering. This is in Norway, so you are correct: Stue refers to the Sonos Beam. I have tried to select Stue, but when I turn off and on the Apple TV once it changes back to Apple TV unfortunately. 

Hi @Airgetlam  . Thanks for answering. This is a 4K-version. When I went to settings it was turned on «Auto». I now changed it to Dolby Digital 5.1. Why can this change the problems? 

It may, or may not cause issues. Normally, when using HDMI-ARC, the receiver device (your Beam) sends a signal to the HDMI-CEC hub (your TV) and identifies itself as 1) a speaker, and 2) a Dolby Digital or Stereo only capable device. The hub (your TV) then passes that information on to any upstream source device (your Apple TV in this instance) and tells it to only send data that the receiving device can process.

However, if you were to switch, at some point in the future, to an optical connection to the Beam, the one way nature of that connection means that the TV, and consequently the Apple TV device no longer has knowledge of what device restrictions are ‘downstream’, so the Apple TV would choose to send any signal it is set to. In the case of Auto, it would send whatever the source is encoded in. If that source is Dolby Atmos, or DTS, or Dolby Digital Plus, the Beam would no longer be able to interpret the sigNail. So doing what you’ve done ensures that if you end up changing the connection type, your Beam will still be able to process the signal being passed to it.

If you’re familiar with the meaning of the phrase ‘belt and suspenders’, that’s what you’ve done. It’s just an extra precautionary step to ensure that there’s no issue with the audio codec coming from the Apple TV.

Rather than step on AjTrek1s help, I’ll bow out, now that we are certain of that aspect of the stream. His problem solving skills are prodigious, I’ll leave you in his capable hands. 

Hi @amnett 

Sorry for not getiing back sooner. Thanks , also to @Airgetlam for dropping the ball back into my lap LOL

However, @Airgetlam was on the right track. Let’s do the following:

1. Disconnect all sources from your LG and unplug them (i.e Beam, AppleTV, Blu-Ray etc)
2.  Factory Reset your Beam as per the instructions in the link:
3.  https://support.sonos.com/s/article/1096?language=en_US
4. Open the Sonos App and go to Add Product
5. Setup Beam via HDMI-ARC. Make sure it’s working properly B4 going to next step
6. Connect the AppleTV to an open HDMI port on the LG
7. Plug-in the AppleTV
8. In AppleTV Audio you should see STUE (Beam) as HDMI...select it.
9. Set Audio format to Auto (If you later have audio issues...select Change Format in this same menu)
10. Your AppleTV audio should remain as set 
11. Connect your Blu-Ray to an avaiblle port and plug it in

Let us know how things sort out.

Cheers!

@AjTrek1 Thanks for good instructions. I can see now on the TV that it doesn’t have a HDMI-ARC-port. The TV is probably too old. Normal HDMI and HDMI/DVI in is the only opportunity. So maybe the best thing to to here is to connect the optical cable from the Beam to the Apple TV (instead of connecting it to the TV). Because then I guess the sound issues will be fixed when they use the Apple TV every day? Because the Blu-ray-player is not in use more than a few times a year.