Change icon and system text size on Windows 10

[sunshine1]

Hello there,
I would appreciate your feedback to the following problem:
The ICON AND SYSTEM TEXT SIZE ON WINDOWS 10 apparently cannot be changed. They are far smaller than in win 8.1.
Change only text Size is grayed out in Win 10. Cannot do anything with it.
I have spent many hours but no success.

In Win 8.1 it was working and I could reduce/increase icon text size on using this.
Not sure why this choice is there if it is grayed out and useless in win 10.
thank you in advance.
sunshine1

[Tante Google]