If you want to add more levels to the drop down or quick launch navigation in a Sharepoint 2013 site, you can do it by making a small change to the master page in use. This technique should work for any type of site (public/private) in any tenant.
Open the site in Sharepoint Designer
Click all Files » Catalogs » Master page
Master pages can’t be edited directly anymore so open the associated HTML MASTER PAGE FILE (which will usually have the same name eg. oslo.html).
Find “MaximumDynamicDisplayLevels=”2” in the grayed out code under “SPM:<Sharepoint:SPNavigationManager”
Change the “2” to how many levels you want.
Save the file, check it in and publish a major version (if checked out) or go to site settings » galleries » master pages and page layouts and publish it from there.
If using a left hand nav (or quick launch), follow the same process only of course with the appropriate master page – Seattle or Berlin.
Ask away in my forum.