If the customer-facing screen on the till is displaying the Aura logo you will need to follow the below steps to change it to solid color background.

Step 1: Right-click on the Start menu in the bottom left corner of the screen, then select settings:

Step 2: Once the Windows Settings are open, select Personalization:

Step 3: Change the drop-down for your background to be a Solid Color:

Step 4: Select Gray dark and close the settings:

This will also change the background of the secondary display.