You can burn captions into the picture or export a separate subtitle file. Burned-in captions always appear, which suits vertical feeds where the platform may not show a subtitle track. A separate .srt file is better for YouTube and anywhere the viewer might want to turn them off or read them in another language.
Because the app knows the script you were reading, the caption text is your actual words rather than a transcription that has guessed at them. That is a meaningful difference for names, jargon and anything a recogniser has not heard before.
Check the timing before you publish, particularly if you paused a lot. Removing the pauses first tightens the timing considerably, because the dead air comes out of both the video and the captions.
