Individual social media icons

See documentation here too:
https://kriesi.at/documentation/enfold/social-share-buttons/#how-to-add-custom-social-icons-to-enfold-options

if there are not too many individual social icons, I would recommend not to use font icons, but to use images (png’s) instead
For this you would have to find a suitable image file for the icon – e.g.:
the whole thing is possible as circle too:

To Register the new Icon on Enfold put this to your child-theme functions.php

function avia_add_custom_social_icon($icons) {
	$icons['Kununu'] = 'kununu';
    return $icons;
}
add_filter('avf_social_icons_options','avia_add_custom_social_icon', 10, 1);

Now you can add on Enfold-Child Options – Social Profiles – the new icon ( it is at the end of the list : link maybe: https://www.kununu.com/ )

to have now the image for that new icon
you had to place this to your quick css
(the image dimensions depends on your other settings for social media icons – standard seem to be 30px):

#top #wrap_all .av-social-link-kununu a:before{
    content: "";
    width: 30px;
    height: 30px;
    float: none !important;
    display: inline-block !important;
    vertical-align: middle;
    background: url(PATH-TO-YOUR-IMAGE/kununu-quad.png) no-repeat center center;
    background-size: contain;
}

/**** hover style - just an example - if you make the image a bit smaller - you can style background-color ***/
#top #wrap_all .av-social-link-kununu:hover a {
-webkit-filter: hue-rotate(180deg);
filter: hue-rotate(180deg)
}

see here in my footer the example: https://webers-testseite.de/#footer

This workout i would only do if i had to add more than one icon to my enfold.
you can upload a svg file to fontello icon : http://fontello.com/
these svgs had to be monochrome – and sometimes do not work correct in fontello because of svg spezicications ( compound path etc. )

then activate these generated font-icons and name the font – then download.
here is that fontello generated zip
https://webers-testseite.de/fontello-bdbd84bd.zip

goto your Enfold-Child – Import/Export and upload that zip to your Enfold via : Icon Font Manager.
Because i named the font : kununu the font-family is then the same kununu

function avia_add_custom_social_icon($icons) {
    $icons['Kununu'] = 'kununu';
    return $icons;
}
add_filter('avf_social_icons_options','avia_add_custom_social_icon', 10, 1);

// Register new icon as a theme icon
function avia_add_custom_icon($icons) {
	$icons['kununu'] = array( 'font' =>'kununu', 'icon' => 'ue800');
	return $icons;
}
add_filter('avf_default_icons','avia_add_custom_icon', 10, 1);

Styling : depends on you.

#top #wrap_all .av-social-link-kununu:hover a{
    color:#fff; 
    background-color:#99c612; 
}