Thanks for reaching out, bigalxyz123. We can help.
It sounds like you are using a third-party app to play your own streaming content from a dedicated or shared personal server. While Apple and Netflix curate their respective content to be able to take advantage of Dolby Atmos, and other surround sound formats, not all content has this option available. If you check out Play audio in Dolby Atmos or surround sound on your Apple TV you'll find that for Apple:
"Apple TV 4K and Apple TV HD automatically play sound in the highest quality that's supported by your home entertainment system setup and that's available with content that you watch.
If your home entertainment system doesn't support the audio format that Apple TV automatically selects, you can manually change the audio format. Go to Settings > Video and Audio > Audio Format and turn on Change Format. From here you can choose the following:
- Dolby Digital 5.1: Plays audio on multiple speakers and a subwoofer, like a 5.1 speaker setup.
- Stereo: Supported audio quality for all televisions, movies, and TV shows that plays sound through a right and left channel."
That said, since you are curating your own content, there may be an opportunity in the streams available on your source media, an opportunity on which audio streams are selected for and encoded, an opportunity for which audio stream is selected on playback, and lastly an opportunity for which types are supported through your third-party software.
Your best bet would be to reach out to the developer for confirmation of support for this feature and additional assistance. Here's How to contact an app developer.
Hope that gets you in the right direction.
Take care!
