You can watch YouTube videos on your TV with 5.1 surround sound. Enjoy YouTube’s library of shows and movies as well as other YouTube content with your supported surround sound system.
Turn on 5.1 surround sound
Once you select a video to play, a player control bar will show. Go to 5.1 surround sound 
Note: The setting will only appear for videos and devices that support 5.1 surround sound. 5.1 in YouTube is supported on all 2021 and later TVs, Chromecast, Apple TV, Roku and most Fire TV devices. In addition, 5.1 surround sound is supported on Xbox Series S|X, Xbox One X, Xbox One S, Xbox One and PlayStation 5. Many 2020 and earlier TVs may also support surround sound - check your device manufacturer to see if your device supports 5.1.