Begin with a language you can comfortably read
For a Malayalam drama, English subtitles may be a useful starting point; for a Hollywood movie, Hindi captions may be more comfortable. There is no universal pairing. Check the available caption languages for that particular viewing edition.
Two kinds of text on screen
Selectable subtitles belong to a track that the player can enable or hide. Burned-in text is already part of the picture. If two translations appear together, turn off the selectable track first to see which text remains.
When captions move out of step
If every line arrives equally late, a subtitle-delay control may help where the player provides one. If the delay changes after an introduction, interval or missing scene, the subtitles may belong to a different cut. A fixed adjustment cannot repair every version mismatch.
Make text easier to follow
Choose a readable size, a contrasting outline or background, and a position that does not cover important action when those settings are available. On a phone, test one scene in landscape orientation. On a television, judge from your seat rather than while standing beside the screen.