why doesn't the the orientation of the screen change with appletv?

Welcome to the Apple Community Leslie.

I'm not really sure what you are asking here. Do you want the image to be sideways when you turn your phone around, it doesn't/shouldn't do that, or do you want the image to stay vertical when you turn the phone round it does/should do that.

Some apps don't rotate, is it an app that's supposed to rotate.