Rotel A14 and LG TV issue

I recently bought a Hotel A14 and hooked it up to my LG TV via optical tousling cable.  When I open the Pandora app on the TV, it successfully feeds the signal and I get sound to my speakers, but with the Netflix, Amazon Prime, Amazon Music and Spotify apps, the sound doesn't work.

I am stumped as to how to fix this.  Does anyone have a clue why this is happening and how to fix it?

Thank you in advance for any tips!
Hi Mep,
With the apps in question;
With one of those apps opened-up and logged in; check to see if there is a "tools" window or "settings" window, in the app itself. Software settings.
I need to check my Samsung; with Prime logged in, to see if there's tools or settings.
Thanks, Scratcha.  I found the culprit.  I needed to change a setting on the TV to PCM, and then everything worked.  Thank you for reaching out.