Hi, I have a Samsung 4k smart TV and the new Apple App has become available. I tried ordering a move from the 4K selection, but only HD options appeared. I have a 50 meg per second Internet speed. An older Apple TV box is also connected. Why can

With Apple TV 4K, in the iTunes Store for movies, 4K and HD titles are the same item to purchase or rent. I would expect it to be the same for new 4K TVs with built-in iTunes Store. (Only SD versions are really a different item purchase.)

Did you actually test the playback resolution of a title with the 4K designation?

Unplug the old Apple TV box temporarily, to avoid confusion about which app is being used. It will not feed 4K content to your TV, ever.