RokNavMenu is the core of all the powerful Voxel menu system. Please ensure you are using the latest version of RokNavMenu, available here.
A static menu system that displays 1st and 2nd level items in the main horizontal menu and further children in the Sidebar.
All Menu Items can be edited from Admin → Menu → Menu Name → Menu Item.
Go to Admin → Menu → A Menu → A Menu Item → Select a Parent Item, and it will appear as a child of it.