Did you configure subtitles in the AppleTV settings the way you want them? If that isn't working with Netflix, try swiping down from the top of the Siri remote while something is playing in Netflix and see if there is a custom setting available. I don't use Netflix myself, by I saw in a review that swiping down shows a hidden menu during playback, same with swiping up. I believe it was in DetroitBorg's review on YouTube about the ATV4.