Enable / Disable Login Pop-up
You can disable login pop-up in the site home by clicking on this checkbox.
Customizing the Login Page
Upload Background Image
You can upload a background image of your choice using this option.
Signup panel text color
Here you can select the text color of your choice which will be reflected on the Login/Signup panel.
Enable / Disable Social Login in the Pop-up
Follow these steps to enable social login on your Moodle site,
Go to Site Administration > Server > OAuth2 Services > Setup Service Providers
Click on any Service that you want to implement and you will be redirected to a page wherein you could implement the setup,
Click on the first link just in case you need detailed information about how to set up this service.