read Control your TV or receiver with your Siri Remote or Apple TV Remote, especially paying attention to this part:
Make sure that HDMI-CEC is on
If some features don't work, check the following:
- Make sure that your TV or receiver offers HDMI-CEC support. For help, ask the TV manufacturer or check the manual.
- Check that HDMI-CEC is turned on in the menu of your TV or receiver. Use the remote that came with your equipment. Since manufacturers often have different names for HDMI-CEC, look for a setting that ends in "Link" or "Sync." Here are some examples:
- LG: SimpLink
- Philips: EasyLink
- Samsung: Anynet+
- Sharp: Aquos Link
- Sony: BRAVIA Sync