Hover on the handbook you would like to change the cover and click on the three dots that appear on the right side.
Select "Settings" from the dropdown menu.
Here you have two options:
Option 1: Select ready to use covers
Option 2: Upload your own custom image
i. Click on "Custom."
ii. Drag and drop your custom image file into the designated area and click continue when you have uploaded your photo.
Click Save changes when you are all set.