A clear label is better than an assumption
The movie name identifies the production. Resolution identifies a particular video setting or edition. HDO Box does not label the entire catalogue as a guaranteed 4K library.
1080p for a comfortable picture
Compare the selected service’s Full HD option with your screen and connection. If it plays smoothly and looks good at your seating distance, you do not need to keep changing settings during the film.
4K and HDR are separate checks
Inspect the actual title offer and supported playback device. Resolution alone does not promise a particular dynamic-range or sound format.
If the picture changes while playing
Some players adapt their bitrate to the connection. Use the available quality settings in the application showing the video. The website’s year and genre filters do not control that player.