Basic WordPress Menu, Navigation & Sitemap:
How to change the Menu /Navigation and Site Map order in WordPress
Depending on the theme used in your WordPress website, you can change the order of the pages using Quick Edit.
If this does not appear to affect the main drop down menu, then you have an independent navigation system, which needs a different approach.
Step by Step Instructions:
Log in and go to Pages:
When you hover over each page title on Edit Pages, there are these links:
Edit | Quick Edit | Trash | View
Click on Quick Edit.
In the example, the Contact page has Order no 4.
You can use decimal points like 2.5 to fine tune the page order.
To make a page into a sub page (that doesn’t appear on the main menu): Click the drop down menu next to ‘Parent’ , then select the page that you want to be the main (parent) page. This will show up if your website shows ‘breadcrumb’ links.