Thanks for your answer.
Yes, I created the shares via the GUI. I did check the box to give same permissions to the subfolders.
I only have one user which is also the owner of my shared folders.
What i want, is that it is not possible for my user to select folder C (in example above), press "delete" and the folder's content is deleted whithout any warning.
How to do so?
I gave the user rwx permissions on folder C but only r-x on folder B. I don't understand what's wrong.