Content > Link Lists > "Header Links"

Placing an icon class in the "Icon Class" field will cause the icons to display on smaller devices.  If a link does not contain this class, it will not show the icon on those devices.

See list of icons here: http://eaglebrookchurch.monkpreview3.com/_assets/fonts/icons/icomoon/  | https://eaglebrookchurch.com/_assets/fonts/icons/icomoon/

Mobile will display the icons only.