Captions are only available on videos where the owner has added them, and on certain videos where YouTube automatically provides them.
First you have to turn Captions ON
If a video has captions, you can turn them on by clicking the captions icon at the bottom of the video. Depending on your location, the captions icon will look like one of the following: or
To turn them off, click the captions icon, then Turn Captions Off.
Select caption language
Choose different caption languages by clicking the captions icon. If the language you’d like isn’t there, you may want to try auto-translated captions, which uses Google Translate to translate the captions.
Here’s how to enable auto-translated captions:
Click on the captions icon at the bottom of the video