For every guide channel and every source, the initial playback audio volume is 100% regardless of set iPhone volume level.
- Set iPhone volume all the way down to zero (mute).
- Tap Guide tab
- Tap a currently playing program
- Tap Watch button
- Playback volume will be loud (seems like 100%).
- Press iPhone volume down button just once and playback volume goes to zero (mute).
- Tap Done to stop playback
- Repeat to play another program
- Volume level again is loud and not muted.