EXCELLENT!

This app is super-simple to use. The only reason people have downvoted it is because there is no clear tutorial. Using the app is simple. Activate, then update posts or pages. For instance, if you want to update the URL slugs for posts, go to the standard WordPress Posts page, select some posts (not too many – I did 100 at a time by viewing 100 posts per page and selecting all posts) and click ‘Bulk actions’ > ‘Edit’ > ‘Apply’. Then simply select update without needing to make any further changes. This will refresh the page and url slugs will be updated to match the post titles. Enjoy!