Change YouTube Icon in Header

Trying to change the YouTube icon in the header using these instructions:https://kriesi.at/documentation/enfold/social-share-buttons/#how-to-add-custom-social-icons-to-enfold-options.

/* Update Youtube Icon */
// Register new icon as a theme icon
function avia_add_custom_icon($icons) {
$icons[‘youtube’] = array( ‘font’ =>’fontello’, ‘icon’ => ‘ue921’);
return $icons;
}
add_filter(‘avf_default_icons’,’avia_add_custom_icon’, 10, 1);
`
// Add new icon as an option for social icons
function avia_add_custom_social_icon($icons) {
$icons[‘youtube’] = ‘youtube’;
return $icons;
}
add_filter(‘avf_social_icons_options’,’avia_add_custom_social_icon’, 10, 1);

Unfortunately, the icon does not show up. Please help.