To change the homepage course list on the Totara Mobile app, you will need to follow these steps:

1. Log in to your Totara site as an administrator and go to the site administration menu.
2. Navigate to the "Mobile app" section and click on "Settings".
3. In the "Homepage" section, you can select the "Courses" option and then choose which courses you want to display on the mobile app home page.
4. You can also choose to display recent courses or favorite courses on the home page.
5. Once you have made your selections, save the changes.

After making these changes, users who log in to the mobile app will see the updated course list on the home page.

Note that the exact steps may vary depending on the version of Totara you are using. If you need further assistance, you can refer to the Totara documentation or contact their support team for help.