Steps to change the loader image or GIF in homepage builder:

1) Navigate to the Site Homepage as Admin user.

2) Click on the Turn Editing on Icon on the Site Homepage page.

3) Now on setting button. Refer to the image attached below.

4) Now in the Home Page settings, you need to upload the loader image or GIF in this section 'Upload loader image for frontpage'

Note: This feature is applicable for Moodle users above version 3.5 and Edwiser RemUI 3.5.x and above.