Learn YouTube SEO tips on how to add closed cations or subtitles but better yet force closed captions CC onto your videos. After forcing your YouTube video closed cations this will then open up your videos to more people and make your YouTube videos easier to watch and understand to perhaps the deaf or hearing impaired.
Step By Step Guide:
You need to login to your YouTube account and open the YouTube Studio.
Then On the left menu, click on Content
Then open the video that you want to work on.
Inside of the the tag section, at the bottom of the page, add this yt:cc=on
Save the YouTube video with the captions forced on .