If it helps, the menu I'm talking about is here:
In the Menus section of the dashboard I have just the top level menu items appearing in the "main" section where you can drag them around and reorder them. But it does not have any of the nested items showing there even though there are drop-down items on the site.
In the pages panel to the left side I can see all my child pages nicely organised and nested.
I don't know why the nested items on my actual menu (under About) don't appear in the edit panel in the menu section and I am having trouble adding a third level menu item.