Hello @Tamas ,

Thanks for reaching out to us in the Instructure Community about the captions for your Canvas Studio videos. I ran a few tests here with my Studio Account to see what options might be possible with setting a default based on the course. My testing results were showing that the language of a course does not affect the captions set as a default. it instead shows that the captions are adjustable based on the person viewing the video, as mentioned here. So the best approach available would be to direct the students/users to turn on the captions in the Studio video settings prior to viewing the video.

I think this is a great Idea that could be potentially developed by the Canvas Engineers!!  We have a space for these types of improvement Ideas linked here that is reviewed by our engineers to develop new updates and features. We ask that you search to see if this has already been suggested as an Idea and upvote the exiting post for this. If there is not one then you can post this as a new Idea once you have ranked up as mentioned on that same page. 

Thanks for reaching out to us, and let us know if you have any other questions related to this!!