The edition sets the starting point
Check the quality offered by the selected service. A high-resolution poster does not establish a 4K video edition, and a 4K display cannot add source detail that the stream does not contain.
Sharpness is not the only consideration
Compare audio, subtitles, aspect ratio and the correct cut of the film. These can matter more than choosing the highest number in a menu. For a dark mystery, readable shadows and clear dialogue can make the evening much more comfortable.
When automatic quality changes
An adaptive player may alter resolution as connection conditions change. If repeated changes interrupt the film, try a lower manual setting where offered and let the session settle. Test another title on the same service if the problem persists.
Use the player you opened
Picture-in-Picture, playback speed, full screen and keyboard shortcuts belong to that service and browser. There is no separate Faragski setting that changes a stream already playing elsewhere.