Down the left-hand side of the Sandvox window is the Site Outline. The top page in the list is the 'Home page' of the site; the first page shown when only a website's address is typed into a browser e.g. www.isawhow.com. The browser understands this to mean www.isawhow.com/index.html and automatically display the index.html page.

It is easy not to realise that in Sandvox, this home page is a Collection page. It contains all the other pages in the site.

The Inspector for the Home page controls the Sorting order of the horizontal Menu Bar for the site.

In the following screengrab, with the Inspector set to Alphabetical, the pages will go from 1 to 7 with the Contact us page at the bottom:

If the Collection: Sorting: is set to Alphabetical the menu order works, but if there is not enough room to include the numbers and words, the menu order will be wrong as seen in this example, note the position of the Contact Us page is not at the bottom:

In this case the sort order needs to be changed to Collection: Sorting: Not Sorted and then manually drag the pages into the correct order.

Site Outline Bug: [Update: fixed in Sandvox 1.6]

I found when doing this do not try and drag a page to the bottom of the list because nothing moves. Instead drag the pages into the middle order of the list and let the bottom page filtering down into its position.

This link goes to my experiment site [Sandvox Sort Order]