Thanks so much for reaching out and thank you for using the Grid-One theme with BoldGrid Post and Page Builder for WordPress!
The social media icons in your “Page Header” are associated with the “Social” navigation menu. You can access this menu in the Customizer by navigating from your WordPress dashboard to Appearance < Customize < Menus < Social Media. From here you can add new social media links or adjust your current ones.
I hope this helps! Please let us know if you have any other questions for us!