Which TV do you have? What are the audio settings on your Apple TV? Which Sonos devices do you have? How is your Apple TV connected to your TV? How is your Sonos connected to the TV?

I have a Samsung smart tv - few years old but still decent enough.

I am using the Apple TV app on the tv and there are no sound settings available that I can find on the in app settings menu.

I am trying to use it with a Sonos beam gen 2 currently but also have several other speakers that I have not yet connected up (currently also having difficulty connecting two subs).

The beam is connected to the tv via an hdmi into the arc port on the tv

The Apple TV’s sound settings aren’t per app, they’re for the entire device. Hold on, let me pull it up…

(Apple’s) Settings - Video and Audio - under the Audio tab (near the bottom of my screen, you may need to scroll down) - Audio Format should be set to auto, Atmos Available. A few rows down from that, ensure that Audio Mode is set to Auto.

Knowing which particular Samsung might help, people could look up the user manual for settings, or if they have that particular model, they might suggest settings. Unfortunately, ‘smart tv’ isn’t enough. 

The Beam gen 2 should be fine. But let’s deal with your other issues first, before delving into why your Gen 3 or Gen 4 subs can’t be doubled up. One Sub should be able to be ‘bonded’ to your Beam. 

OP is using the AppleTV app, not the hardware.

​@Darren1987 - When you moved home, did you simply just unplug the Sonos devices and now trying to get them working in your new home with different router? Are any Sonos devices wired to the router or do you have a wireless setup? The Beam may think it is still bonded with the Sub(s) but the Sub(s) have been assigned different IP address following move so the Beam isn’t currently seeing them.

If you can use the same SSID/password as your previous router, do that, otherwise see if this guide helps https://support.sonos.com/en-gb/article/connect-sonos-to-a-new-router-or-wi-fi-network

Hi

Yes exactly, I just unplugged and left. Now I am trying to get them working with the new wifi.

I have managed to get the beam, arc and two subs connected and working. 
However, what is strange is that on the Apple TV app the Sonos system works when viewing the trailers for programmes on the main menu, but does not work for watching the actual programmes.

I believe the trailers may be in Dolby 5.1 whereas the programmes are in Dolby atmos. I don’t know if this is the reason and how to resolve it though.

The Sonos seems to work on most other platforms, other than my Amazon fire stick.

In the last house, on the previous WiFi I had no issues with any platform whatsoever so it is strange that there is now an issue.

I would now look at the TV’s audio settings and see if adjusting them results in the actual programme audio being heard.