Impossible to know why but you can’t change anymore : Subtittle or Audio in
Amazon PrimeVideo app for IOS (in my case IPAD Pro with IOS 11)
Crash the app when i try …
– I also try to restart the Ipad
– I also try to delete & resintall the  Amazon Prime Video IOS app
No way …

So i try to change Subtittle via the Brother (Chrome)  using the Web Version of Amazon Prime Video and now it’s Back … I can Change again normaly the Subtittle & Audio …
I just want to share and make you don’t lose time like me 😉

Enjoy 🙂