Hi @Cherme
Welcome to the community!
I have translated your post as this is a Global forum all posts/replies must be in English 
It sounds like you may have magnification gestures activated which can cause this to happen.
To turn this off just do the following just head to Settings > Accessibility > Magnification.
From here you should be able to turn the magnification off.
If you have any further issues, let me know 
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