You can change the order of your menu items on your navigation menu from your website admin.
From the admin, click on the Navigation Menu icon.
Click Edit Navigation Menu Order.
Select the item and use the Move Up or Move Down buttons to position the menu item.
Click Save Changes.
Note: If you are using categories, categories are always displayed on your navigation menu below your menu items and cannot be intermingled with your menu items. The best way in this case to order your menu would be to add as many menu items as possible to categories.