Shadows question

[andy90]

Hy there,
just have question about contact (occlusion) shadows and ground shadows.
How to control ground shadows and contact shadows strength?

The simple way to this should be as it is answered in the post before, but the problem is i can't get it work...
I tried the same method as in this post (link below), but nothing is happening when is set to the same settings?

https://www.keyshot.com/forum/index.php?topic=12984.0