@toerfiets: Hello Hans,
In the Social Header Right you will need to select menu with Social Media links. You seem to be selecting the same menu that you have selected as the Header Right menu.

Go to => Appearance => Customize => Menus => View All Location => Social Header Right Menu => Edit Menu => Add Items => Custom Links => Insert the link to your Social Media and Text and Publish.

Let me know if this works out!
Kind Regards,