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, this part is added from the Mega Footer plugin, that will allow to add unlimited elements to every page.