Beam to older aquos sharp 70” arc TV.

I’d also suggest not using the Andy Griffith Show for testing, I suspect it is broadcast in mono, not even stereo, and you won’t get a ‘better’ codec from that. Make sure you’re watching a recent movie with an Atmos soundtrack when making these suggested adjustments. The options will often be ‘grayed out’ when the content being watched doesn’t have the necessary data. 

Yea I was just taking menu picks.  I see no options to select pcm or Dolby. I did try optical but no difference 

And this but it does nothing.  

I wouldn’t expect the Food Network to bother broadcasting in anything beyond stereo. I’d still recommend a recent movie that is being broadcast with an Atmos soundtrack, as I said before. 

My stream service has uhd fhd channels. Tried them and firestick 4k.  See no option for Dolby. Or even pcm.  

I’ll try a blue ray on Xbox.  That should tell us something. 

Played blue ray through Xbox last night and fire tv 4k had an audio diagnostic I ran. It showed only pcm  and same on Xbox.  Idk. 

@Mikey67

All your testing imo indicates that passthrough on the tv isn’t supported. 
As supposed the tv manual seems to have no specific information about digital audio out for hdmi sources. 

Thanks. Unless I get better info. I just wonder why have a HDMI arc if it doesn’t improve anything 

On two of my old Vizio TVs, I had HDMI ports that wouldn’t pass a Dolby Digital plus or higher through to the ARC output. The maximum they could pass through was Dolby Digital. Only the internal apps were ‘allowed’ to send out those higher formats. I’ve gotten rid of both of those TVs.