Problems with Netflix Sound?

Have the following problem with Netflix. If I go to Netflix and come to the overview where films are series etc, and then go to a film without clicking on it, so that the credits are played, there's sound. But when I click on the film, the sound is gone…

does anyone know that or does anyone have a solution?

(watch the fireTv stick, and everything else YouTube twitch etc works)

Have to look where you can set the language and subtitles. There should be German 5.1, do it in German only

Helped, thanks 🤝