This article explains how to change the language on Netflix using the Netflix website. You cannot change the Netflix language on mobile devices.

If you open Netflix and see that everyone on the screen is speaking a language that you don’t understand, you need to change the primary language. To fix this, go to the settings and fix it via your profile on the Netflix website.

While frustrating, you will need to log in to the website to restore the language associated with your Netflix profile. If you try to do this from a phone or tablet, the option to choose a different language will not appear.

Select Manage Profiles on Netflix.com. If you don't see that option, select your profile image in the upper right corner of Netflix to find it in the menu.