air ios stagewebview youtube video without sound

I developed an app for IOS  with flash air 15.0

I used StageWebView  to play youtube video in my app. On some ipad  I have video +sound and on other only video without sound.

Is someone have a track for a solution?

You can find my app on the apple store or play store , find :

"fare, le mond de la propreté"

Best regards

Jean Luc