If your site has more pages than you can fit on the navigation bar our system will automatically create a More link and add all of your new pages as subpages of this More link.
This works reasonably well, but a better option is to avoid this More link entirely by making any excess pages of your site sub-pages of other pages. This gives you more control over the structure of the site.
How? By using the option found under the Pages tab. Drag a page underneath and to the right of another page in the list to create a subpage.