Dolby PCM 5.1 instead of Dolby Atmos

What movies did you play? In which language? On what services? On what subscription plan? Using apps on the TV or an external player?

I'm using the built in app via the Samsung TV. Tried it on Disney+, Amazon prime, Hulu. Is there a particular movie with dolby atmos I should try it on?

Also, what is the difference between dolby PCM 5.1 better and dolby digital plus 5.1? 

My recent experience of getting atmos…
on new Samsung S90D OLED TV

Netflix
Built in app on TV (premium level subscription we already had) - Amos built in w/ prior upgrade sub. Nice, worked from the start. Thank you, Netflix! Gold Star and sugar cookie to you.

Max
Built in app on TV - A sh*t show! Took a long time w/ customer support to realize (even after canceling original sub thru Youtube TV source) after upgrading to "ad free level"- still no atmos... until... it was explained, finally, that there is no atmos if Max is w/ ANY kind of bundle - WTH!?
So, they had to refund the bundle bill, cancel me, then I had to create a new stand alone Max account ... and finally Atmos works on Max! Fine but they explain NONE of this when you first sign up - they, and most providers, steer one to bundles. So that was fun undoing all of that. SMH

Paramount Plus
Built in app on TV - Of course I then upgraded to P+ Showtime (ad free level) - to get all that great Atmos content, right? (Saving Private Ryan only shows up in Sonos app as 5.1 surround)
Nope - black eye on the service from Paramount - Samsung does not make their very short list of supported devices (Fire Stick is not even on that list - a possible work around for me as we use Samsung apps built into TV - but nope), only Fire TV - no they aren't the same according to the Internet.

Ha! The P+ chat person at the end sent me a link to CBS.com to send feedback - laughingly HAD to select a show (picked Matlock) to be able to provide feedback - not a P+ /Atmos category in sight.
How special that the software engineers at P+ can't be bothered to get atmos working w/ a tiny little brand like Samsung.

E-mails to paramount plus about atmos  went unanswered.

I eventually relented and purchased Apple TV 4K - Paramount+ on ATV is now atmos ready. And it works.
The open software Tizen that Samsung uses is not as high priority w/ the streamers like dedicated devices like Apple TV. 
 

Amazon Prime only sends you Atmos if you pay for the “Ad free” option.

Please don’t ask me why Atmos is enabled by Ad-Free or I’ll start banging my head again.

In addition to the above, you need to go into the audio settings on your TV.
HDMI-eARC mode: AUTO
Digital output format: Pass-Through

I would also recommend that you make sure your TV is updated with the latest software/firmware. The best way is to check on Samsung's website as the TV does not always download the latest.