Enable eARC Mode on your TV and set Digital Audio Out to Auto 1 and Passthrough to Auto.

FYI… the Apple Music, YouTube, and ESPN apps only support stereo audio.

Are your sure? I have no problems getting Dolby content straight from the apps out of the google tv but as I soon as I play content on the same apps from the Apple TV all I get is stereo.

I will try this and give an update if it works or not.

I am 100% sure that YouTube and Apple Music only supports stereo audio. But beginning in June, Apple Music will begin offering some music in Dolby Atmos.

I am 99% sure ESPN only supports stereo audio, but I don’t have a ESPN+ subscription so I don’t know if the programming offered on ESPN+ is any different.

No ESPN+ just the regular ESPN app. On the google tv it plays Dolby digital plus 2.0 and from the Apple TV 4K it plays stereo pcm.

Dolby Digital Plus 2.0 is still stereo. Your TV must be converting the stereo PCM signal to Dolby Digital Plus.

Makes sense. Now is there any way I can convert it to Dolby digital plus from the Apple TV. Even though you just said they are both stereo there’s a big difference in sound between DD plus 2.0 and stereo pcm. 

Probably not. The Apple TV 4K uses Dolby MAT which is a form of PCM. So when you have Change Format turned off for Dolby Atmos audio, the only audio you will get from the Apple TV is stereo PCM, multichannel PCM, or Dolby Atmos. You can try turning Change Format on and have audio re-encoded as Dolby Digital 5.1, but I think you will still get stereo PCM audio from stereo sources.

Yes you are correct. I only get stereo PCM from stereo sources if change format is on. If change format is turned off and I play a movie on Netflix or streaming app that has Dolby vision and not Dolby atmos it plays as multichannel pcm 5.0 unless I turn on change format on and set it at Dolby digital 5.0 which is annoying because I have to switch it depending on what I am watching. Thank you for all your help!!

To be perfectly honest, I don’t understand a lot of what was just tossed around in the above back and forth, but I THINK this explains what I’m experiencing, which is:

I have an Apple TV 4K connected to a 2017 Samsung television.  I have a Beam connected to the Samsung and a pair of Play:1s set up as a surround sound pair with the Beam.  Works great for whatever is playing on the television and also works great when I play music via the Sonos app.

What I just realized, however, is that the two Play:1s are silent when I use the Apple Music app on the Apple TV to play music.

The Beam is connected to the one HDMI ARC port on the Samsung (as it should be).  The Apple TV is connected to a “regular” HDMI port.

Does this setup explain why the Play:1s don’t function as surround sound when playing Apple Music from the Apple TV?  Not a huge deal for me, but I was perplexed.

When you play music, the signal being fed to the Beam is stereo, not a 5.1 signal. So the surround speakers would not be getting any channel information. Because you’re using the AppleTV to play the music, you can’t use the ‘music’ settings for the surrounds, as the Sonos only is aware it is receiving a signal via HDMI ARC, and has no idea what kind of signal is being passed to it. 

If, rather than using the Apple TV as a source for your music, you were to use the features in the Sonos controller to access the music, then you could use those additional features.

It’s 1 year later and I have had this problem all along too. Beam + 2 Sonos One’s connected. HDMI-A connection to sony, and Apple TV 4K to HDMI 1. TV set to use “audio system” instead of TV Speakers.

for Apple TV I have to manually select my Sonos named system because the default is the TV direct connection, which only plays from the beam. If I change apps, I have to do it again. If I walk away and come back 15 mins later, I have to do it again. It drives me batsh*t but I have yet to figure out how to change it no matter settings I try on both the tv and Apple.
 

What would be most convenient is If I could just set the default Apple audio output to my sonos system instead of the tv but it won’t allow me to do that for some reason! 
 

is there a solution for this because I have tried the above- but btw, isn’t a beam + 2 speakers a 3.0 system and not 5.1?