Here's what you need
Set up home theater audio
- Use your iPhone, iPad, or iPod touch to put your Apple TV and HomePod in the same room in the Home app. If you want to use two HomePod speakers, create a stereo pair, then put the stereo pair in the same room as your Apple TV in the Home app.
- Turn on your Apple TV. You'll be asked if you want to Use HomePod as TV Speakers. Select Use as TV Speakers to turn on home theater audio.
If you don't see the setup screen on Apple TV, you can manually turn on home theater audio with your Apple TV or your iPhone, iPad, or iPod touch.
With Apple TV: From the Home screen on Apple TV, select Settings > Video and Audio > Default Audio Output. Select the room with your HomePod or stereo pair.
With iPhone, iPad, or iPod touch: In the Home app, press and hold Apple TV, then scroll down and tap Default Audio Output. Select the room with your HomePod or stereo pair. Tap Back, then tap Done.