To edit the footer go to Theme Customization -> Footer Customization.
This field accepts plain text and A link tags. Other html will be stripped for security.
You can override global colors set previously in the customizer to best fit your needs.
To set a footer menu, use the footer locations in Appearance > Menu > Locations.
You can add unlimited footer rows using the QantumThemes MegaMenu plugin, explained in its specific documentation page of this manual. For instance: