How to get Video+Sub in same one file?

[Eleve]

Hello! So I do wonder if someone here could perhaps help me with an issue regarding VLC?
I thought that I would give it a shot and I would be really happy if someone would like to.

So... I got this movie but it is in all english audio and I would like to watch it together with my family but unfortunally they do not understand enligsh, so I thought that I could add a subtitle to the movie in our native language so that we all could watch it and understand.
I tried to click the Convert/Save option, then I selected the movie file as well as the subtitle file below. I then proceeded to where I could select source, profile and all this, I went with the pre-selected profile which were: Video - H.264 + MP3 (MP4)
It started to convert my movie, when I later opened up the new movie file there were no sound or subtitles, the image were perfect but ya, not really what I wanted it to be like.
So I wonder what I did wrong or if this is the way to go at all? Simply I would just like to add subtitles to my movie, usually it is just to select the subtitles file but you see, I want the sub completely baked in with the movie because I can not play the movie through VLC when I later take it with USB to watch on the television, it does not work with VLC on the TV, so it has to be only ONE file with sub baked in.
Or does it work to stream the movie from my computer with VLC to the Television somehow?

As you see, I have no clue! So I am most thankful for any help at all about this so that we all can watch the movie together to night after dinner!

Thanks!

[mangup]

1. Why not simply open subtitles from VLC menu item "Add subtitles file..."?
2. Nevertheless, you can use MP4Box tool from console or via UI (https://www.techwalla.com/articles/how-to-add-subtitles-to-mp4-files)