To show social media links in the header top bar or to customize those links, you must have checked the ‘Show the top bar in header‘ setting in the ‘Header Top Bar’ section. If you don’t know this, check this link.

To add social media links to your web site, follow these steps:

• Log in to your WordPress admin dashboard.
• Go to ‘Appearance > Customize‘.
• Go to ‘Header Options > Social Media Links‘.
• Here, enter your full social medial links. e.g. https://www.facebook.com/WordPress/

If you want to hide social media links in header top bar, uncheck first setting ‘Show social media links in header top bar’.