This plugin allows you to re-order your pages. It is automatically activated for you. Go to the Pages > Page Order menu, and there you can drag and drop your pages in the order you prefer. Keep in mind that if you are using a custom menu (handled in Appearance > Menus), changing the order of your pages here will not affect the order they appear in your navigation menu.
More information: https://wordpress.org/plugins/cms-page-order/