The navigation items could be used as a link, or as a directory with sub-menus. The main items can be reordered at any time, however, the sub-menus are set by creation order.
Access the navigation from Site builder -> Site Navigation.
To edit click an item from the list, or create a new one by clicking “Create new navigation item”.
The title is the one showing in the navigation.
The type could be a predefined page (Home, Contact, Store, Service, Blog, Playlist) or a custom one (Other), where the URL is specified by the user. If a collection type predefined page is selected, a drop-down will appear to specify the collection.
To add a sub-menu to the navigation item click the blue "+" button. Then apply the same principle to specify the item title and URL.
The app navigation is completely automatically generated, because of the different routing strategies implemented in mobile applications.
It will create new navigation items according to the existing collections (stores, services, blogs, and videos). For custom pages, you can decide if you wish to show them in the mobile app, by not marking it as a parital.