On the left side, you can see the categories of the first category tree.
Click on a category in order to edit its access control list.
This access control list consists of a set of permission entries. Above the list, you see the form to create a new permission entry. Here you select which action is to be permitted or not permitted for which user or which group. Clicking on "create entry" adds the entry to the list.
In order to check the permissions, the program goes through the respective list from top to bottom. Thus, if you permit an action first, but forbid it further down, the lowest entry in the list is the one that counts - i.e. this action is forbidden.
To change these entries in the list according to your desired order use the "drag point" to the right of the entries. Click on the drag point, keep the mouse button pressed, and drag the entry to its new position.