Ok, at least I know which setting in the backend is responsible:
Theme Editor -> Homepage -> Image with Textoverlay -> Area Height
=> If I select the option "Fit to picture" in the area height, the CTA button is always centered in the desktop view. If I choose one of the other options, the position of the CTA button also changes in the desktop view.
In the mobile view, I can change the position of the CTA using the codes, these now fit.
Can I change the position problem for the desktop view as well? I need the "Fi to Picture" Option.