Inserting pages linked to footer menu

I have set up a top menu (primary) and a footer menu (for things like privacy policy and terms & conditions).

How do I add pages that link to the footer menu items? When I go to Add Page, it only allows me to place the page under one of the primary (top) menu items.

Edited to add: it seems that all of the Custom menu links I created are affected by this issue, which includes all the footer menu links plus one top (primary) menu link which I created as a custom link.

Never mind, I worked it out eventually!