Open Settings on Apple TV
Go to Remotes and Devices
Select Volume Control
Choose the desired TV or receiver
Go to Learn Remote if available
Follow the on-screen prompts
Point the Apple TV remote at the TV or receiver
Press the requested buttons when prompted
Save the learned remote settings
Restart Apple TV if needed
Unpair the remote if it is not responding
Re-pair the remote by holding Back and Volume Up for about 5 seconds
Charge the remote if the battery is low
Update Apple TV software if remapping is not working
Reset the remote by restarting Apple TV and pairing again