Hi,
Then, you have to look under the "products options" tab of the menu item settings page, not the "categories options" tab.
There, you'll have another "sub elements filter" setting and you want it to be set to "direct sub elements" as to only get the products directly attached to the current category displayed, and not also the products of the sub categories.
The "categories options" tab is for the categories listing, while the "products options" tab is for the display of the products listing of the menu item.