no surround sound from YouTube

YouTube is normally only stereo. There are 5.1 test samples online. 

Ty for fast reply I’ll look for 1  online I did do search on YouTube for a 5.1 test

I’ve not found a true 5.1 yet.  Alll I get is Dolby 2.0

Searching is useless, because even the YouTube videos that claim to be 5.1 are only in stereo 2.0.  They are automatically downgraded when uploaded in order to save space.  Sometimes the videos marked as 5.1 or Atmos offer a download of the real thing, but that is not standard. 

If you search for Dolby Labs in a service that does provide working files you will find some to use. Amazon Music offers a nice selection if you have the service level that enables Atmos.

https://www.dolby.com/en-gb/about/support/guide/downloadable-dolby-atmos-trailers/

Check the link above for Atmos trailers you can download.

He is asking about DD5.1

youttube DD5.1 tests have always worked great on my playbar play1s and sub..

The OP has a fully Atmos capable system.  If it plays Atmos, it will play 5.1.  Plus, Atmos will play as 5.1 if the system isn’t capable.

Ty for everyone’s helpful input now I have my arc ultra 2xera300 and sub in app do I need to do anything in app or just leave it

thanks

Once added it is time to start fiddling with the sound adjustments, always go for what sounds right to you in your room. Cribbing numbers from someone is rarely optimal.

I like to start with a good Atmos test and get the channels balanced, particularly the height. Then work on Sub levels, you need good content with lots of lower than 100 Hz sound.  Next I tweak the tone controls and check out the Loudness comsensation option. 

Check your music service for Dolby Labs test tracks, aside from the iffy YouTube offerings they are usually a great starting point.

I'm enjoying some old Bach (Vox Box stereo edition) organ music this evening and intend to switch to the Concordia Organ collection tomorrow, mine is off the CD set but if it is streaming that is good too. Old school, when the spouse is out, Bachman Turner and Iron Butterfly get some play time.

 Bottom line make your ears happy, maybe try to make the spouse happy too.