How do I enable subtitles on movies streamed to Apple TV?

I have subtitles available when I watch a movie on my computer, but not when I stream them to my Apple TV. I just bought an Italian opera on iTunes for $25, and am not able to get the English subtitles. Usually I buy DVDs of operas and just turn on the subtitles, but this time I decided to get it on iTunes. I have also tried to put subtitles (for hearing impaired) for movies in English and can only get them on my computer. Any help would be appreciated. Otherwise I just wasted $25. Thanks.