Posts are saved by the published date, with the most recent date being the first post to appear on the page. If you would like to change the order of your posts, you need to change the publish date so that it falls in line with the order you want it to appear.
Using Quick Edit
When you hover over a post name, a menu will appear below the title giving you the option to select Quick Edit. This will save you time from having to open each post in order to change the publish date.
If you select Quick Edit, you will be given the screen below where you are able to quickly change the publish date and click Update. (You can also use quick edit to apply a category, tag, change the post name or status & make the post password protected or private.)
Once you update, your post will appear in the new order according to date with the most recent being shown first.