When switching a lot between the German and US keyboard layout (which is much nicer to program), the switched z and y keys cause frequent mistakes. Therefore, I switch both keys in the German layout. An easy way to do this is to use the ukelele keyboard layout editor, essentially following the instructions of this SO thread.

I did the work for you, you can download this bundle. Double click on the saved directory/bundle and select Install for current user. Then head to your keyboard settings and select German standard qwerty.