Hello Boden1976,
Based on your post, you are viewing something via Yahoo and Google in German, but prefer them to be another language.
To clarify, are these the Yahoo and Gmail apps, the websites in Safari or something else?
If they are the websites in Safari, you may consider checking if the URL you are using is the correct one for the region you want. You may also want to clear Safari’s cache/website data, etc. Here’s how - Clear the history and cookies from Safari on your iPhone, iPad, or iPod touch
Thank you.