Web version icon for the subtitles
The available languages and subtitles are indicated in the description of each movie.
The icon of CC is only to switch on or off the subtitles. So not to choose the language of subtitles.
To change subtitles or audio, click on the cog icon at the bottom right of the player window and select the language of your choice. Under Captions, you can choose the language of your subtitles.
Smartphone version icon for the subtitles
The icon on an Android smartphone is a rectangle with lines.
The icon on an Apple smartphone is a text bubble with audio & subtitles.