Look at the actual video offer
A sharp poster says nothing about the resolution of the film behind a viewing offer. Check the chosen edition and supported devices. HD usually refers to 720p or 1080p; consumer 4K commonly means 3840 by 2160 pixels. High dynamic range describes another aspect of the picture and is not simply a second name for resolution.
When the highest setting is not the best result
A stable picture can be more enjoyable than one that repeatedly pauses. An adaptive player may change quality as the connection changes. If it offers a manual setting, try a lower one during interruptions before changing unrelated television controls.
The larger-screen chain
For 4K, the service, plan, title, application and display may all matter. A laptop connection adds its output capability and cable path. Check the viewing service’s requirements rather than assuming a television’s 4K label settles every part of the setup.
For mobile streaming, consider data use alongside sharpness. For dialogue that is difficult to follow, changing resolution will not replace the correct subtitle or audio choice.