I know this is the wrong forum but I don't know where to turn.
If I download a torrent of an English movie that has subtitles when a foreign language is spoken, on my PC I can see the subtitles but if I watch the fime on my TV off a USB stick, I cannot see the subtitles.
The download is a single file with no separate file for the subtitles.
Whats should I do to see the subtitles?

It sounds like you have a .mkv video file with bundled subtitles.

1) Burn the subtitles into the video. This method is inconvenient but is guaranteed to work. You can use Handbrake to do this.

https://handbrake.fr/docs/en/latest/advanced/subtitles.html


2) Search for information about your TV. You might be able to load subtitles from an external file such as srt subtitle format. A program called gMKVextractGUI will let you extract the bundled subtitle file. There are free online websites that will convert the subtitle file to whatever format you need.

https://subtitletools.com/

https://mkvtoolnix.download/

https://sourceforge.net/projects/gmkvextractgui/

MPC-HC will automatically show subtitles if they're in the preferred language. On the TV you probably need to enable them yourself, there must be buttons on the TV remote.
...unless you asked why your TV does not at all recognize subtitles embedded in the file.

Well, I found a very easy solution. I copy the film to my mobile and cast it to the TV by wireless projection.
All good!
Thanks for taking the trouble to comment!