Permalink Question

Hello,
When I give a new post a title, then add image and words, then publish, the permalink has the title in the permalink name.
If I edit the post and change the title, then publish, the old name is still in the permalink. Why doesn’t the new post name become part of the permalink?

I just had a problem with a post. When anyone tried to go to the comments page, there was a 404 message. In all past posts the comments button sent everyone to the comments page(normal).

I then deleted current post and created new post with the same info and everything works fine. Any ideas on the reason for the 404 page?

here is the site: https://whereisbuddylee.com