1. Check the video service website or app from which the show or movie is playing. Some services have preset subtitles enabled, meaning that subtitles cannot be turned off.
2. Check if your Smart TV’s language setting for the show or movie matches the language set for the subtitles file. If a different language is set, the videos will not display the desired subtitles.
3. Check the video service's website or app if subtitles can be manually selected and enabled. This is usually an option located in the Settings menu.
4. If a specific subtitles file was created, verify that it was loaded onto the video service account correctly, and to the proper location.
5. Download a different version of the same subtitles file to see if the issue is the file itself.
6. Check if the file encoding type is supported by your Smart TV, as certain subtitles files only work with specific encoding types.