If you still have the original working remote of your Sound Bar / Receiver / TV, you can use the Learning feature of the Apple TV. Go to Settings > Remotes and Devices > Volume Control and select Learn New Device. You can then teach the Apple TV the Volume Up, Down and Mute commands by pointing the original remote toward it and press the relevant keys. These settings will now be transferred to the One For All Apple TV Replacement Remote. Please note that you may need to restart the Apple TV for this to take effect.
