WordPress URL Problems After Change it
You can do this with 301 redirects. There is a nice easy plugin that will allow you to do this. https://wordpress.org/plugins/simple-301-redirects/ If you want to do it on a little lower level you can edit your .htaccess file with the structure you require. Yoast provides a easy to use generator available here: https://yoast.com/wp-content/permalink-helper.php