Hi Sencera Greii,
Are you configuring those items in the parent category? The children categories items configuration works when you configure it at the parent level. One directory above it, if you're configuring it in the current category then it works for categories below it.
As for the menu item parameter, it will become active when you select to display multiple categories, if you select only a single category then K2 uses the default category level settings and not the menu item settings.
K2 Rocks \m/