Log in to your WP Admin panel.
Navigate to Divi>Theme Customizer.
You can do this from the Admin Panel menu,
or also from the front using the editing bar.
Select “General Settings” from the Theme Customizer options.
From there, select “Site Identity”.
Under “SITE ICON”, you can click to select a site icon, or change an existing one. Select (or upload and select) from the Media Library.
Publish the changes.