Update a subtitle on your account with the specified parameters. Don't forget to specify PUT as the request method as GET will call the show action rather than update.
https://streamio.com/api/v1/subtitles/subtitle_id.format
PUT
204
Just remember to PUT and you'll be fine.
curl -u username:password \ -X PUT \ -d "title=Swedish&language=sv" \ https://streamio.com/api/v1/subtitles/4c483ea1bf4b9802c5000029.json