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The Footer information of a site is located in the Settings page under the Footer tab: 

EditFooter1.png

For a new site:

If the site is new, make sure to check "Use Local Pages in Menu and Footer" in the tab "Menu Information" to overrule the Global footer, as shown below:

 

EditFooter2.png

Social media 

At the bottom of this page, the social media links of the website can be added:

EditFooter3.png

 

The links will automatically be turned into social media icons: 

EditFooter4.png