When lying on the bed with my head on the pillow, I basically can't use my (mi4) phone: if I hold it upright, it goes to regular portrait mode and it's not aligned with my eyes (my head is on the pillow). If held upside down, regular portrait too. If held horizontally (top & bottom of the phone facing the walls) it switches to landscape, still not aligned with my eyes. In fact, it is entirely incompatible with this body/head position.
How is that possible ? Using a phone in this position is incredibly common yet you just can't ! My Lumia 520 (Windows) understood that the phone upside down means the user is lying on his/her bed, head on pillow, thus switched to landscape, so I could watch YT videos and browse websites in landscape.
Anyway, is there an app or anything to, for example, force the phone to stay in landscape when phone is upside-down ?