There are three main ways to access the Divi's changelog
With a direct URL link
From the WordPress Dashboard > Themes page
From the link available in the Elegant Theme's account
Accessing the changelog with a direct URL
Bookmark the page for further usage
Accessing the changelog WordPress Dashboard > Themes page
Go to WordPress Dashboard
Go to Appearance > Themes
Hover over Divi and click on Theme Details
If the Divi theme is not using the latest version, a text link: View version x.x details will appear.
Clicking on that link will open the changelog details.
Accessing the changelog from Elegant Theme's account page
Login to your Elegant theme's account
Head over to the Members Area page
Click on the View Changelog link, which is the last link from the box.