I was watching The Force Awakens this evening and accidentally hit something on the Apple TV remote app on my iPhone which removes the letterbox bars. For the life of me I can’t fogure out what I did or how to get the letterbox back. Help!
Tap twice with two fingers, holding on the second tap. Then push up or down to increase\decrease zoom. The accessibility settings (General > Accessibility > Zoom) can be set to eliminate or reduce zoom level. I set mine to 2X max zoom, but rarely use it, mainly just reading show details or app info in App Store from across the room.