Thank you, PS, for your answer.
Just a few minutes ago i found, that the problem does not basically exist on the Mac, but that it is a problem with the visual editor in the lazarus IDE on the mac. So the editor doesn't show changed TEdit properties, but the finished application shows everything correctly in its runtime environment. So it's a bit harder to create a visual design. I found some other things where the visual editor doesn't display correctly, where the program runs and displays correctly. I will collect them and submit them as bug reports.