Please follow the steps below:

- Locate the learndash-sidebar.php file in your BuddyBoss theme. You can find it here: /buddyboss-theme/learndash/ld30/learndash-sidebar.php

- Copy this file to your child theme directory, creating the same folder structure. The path should be: /buddyboss-child-theme/learndash/ld30/learndash-sidebar.php

- Open the file in your code editor. Then, use your browser's inspect element tool to find the current icon class name in the sidebar.

- Replace the icon class with your preferred icon class in the file.

- Lastly, make sure your child theme is activated to see the changes reflected on your site.