If you're using Simple Blog, your blog post permalink automatically updates when you change the title of your blog post.
The URLs of your blog posts will automatically show up as yourcustomdomain.com/blog/blog-title.
Customizing Your Blog Post Permalink
You also have the option to customize the permalinks for your blog posts. In the blog post editor, click the SETTINGS button, select the “Use custom URL” option, and enter your blog post permalink. Don't forget to "SAVE".
Click "Publish" > "Publish Now" so your blog post URL will update immediately.