To change the background of the Admin Login Panel and User Login Panel, go to the side menu bar and select System Settings > General Settings; in the general settings, you can see the third option, "Login Page Background."

In this feature, you can change the background of the login Admin Panel as well as the User Panel. You just need to click on the Update button for the login background image you want to change, and the admin or user login page background model will be opened. Now choose the relevant image for the background, and your admin and user panel backgrounds will be successfully changed.