what is the best setting for audio output on Apple TV

I have the latest Apple TV connected to a Yamaha Aventage AV Receiver. We watch a lot of content on Peacock, Paramount+, other "TV" content apps. We often have very muddy dialog to the point where we turn on CC.

I was researching upgraded speakers and receivers when I noticed that the receiver shows "PCM" when I let the ATV choose the best format, and this sounds best when I choose "surround" as the audio processing setting (similar to Dolby Surround). I usually had my DSP settings on "standard" assuming I was usually getting 5.1 input.

If I force the ATV to output Dolby 5.1 this shows up on my receiver but doesn't sound as good as the surround setting. I assume the Yamaha is better at this upsampling than the ATV?

My question is this: what's the best setup? If I let the ATV choose, and set my receiver to "surround", the receiver will "decode" 2 channel PCM and will automatically switch to 5.1 if it senses a a multichannel signal. If I set the ATV to 5.1 I will always get a 5.1 signal and can tune my settings accordingly.

It is ridiculous that the streaming services don't always output multichannel audio for the price they charge!