If you are wanting to change the order of your top level pages, there is an easy way to do this!
 

1.  All you need to do is simply click on the directional arrows at the end of your navigation bar (you will need to be in edit mode to do this)

 

2. From there, you can shift the pages up and down as you please – Simply select them, and use the arrows to shift their position:

 


3. Publish Changes to save