Click the "CC" or speech bubble icon directly in the video player during playback; it often defaults to "Off".
Finding subtitles for varies depending on whether you are streaming it or using local media files. Streaming Services Halt and Catch Fire(2014)199 Available subtitles
If you have your own video files and need to add external subtitle files (usually in .srt format), these communities are the primary sources: Click the "CC" or speech bubble icon directly