You are not doing it right :) I see in the code on your website that you have some
class="fa-fa fa-comments-o ..." ... That is CSS code for your own custom icons, and cannot be used with the X3 data icons, which simply use
data-icon="name" (not classes), and are rendered by javascript. Furthermore, it seems you have added CSS classes into the data-icon attribute
data-icon="fa fa-comments-o". If you click the (?) button for custom footer, you will find instructions.
Basically the format looks like this, where data-icon is a simple NAME without spaces from font-awesome. Not CSS classes.
<a href="LINK" data-icon="ICON" data-color="#AABBCC" title="HELLO"></a>
For example:
<a href="/comments/" data-icon="comments-o" data-color="#AABBCC" title="Comments"></a>
As you can see, data-icon is simply the name, identical to the names in the overview below:
https://fontawesome.com/v4.7.0/icons/