New Google+ Logo

by the way : on documentation it is also not correct.
The font-name is entypo-fontello not only fontello !

1) if you had to have the new icon – go to fontello : Link
2) in fontawesome there are these new signs – choose theme (best all 3)
3) name the font on top ( i named it gplus)
4) download the created zip file and
5) Go to your enfold import/export – and import that fontello font (it is now gplus font-name)
6) (you have to know the new code of the wanted icon) – f.e. create a new page and insert an iconbox and on hovering in the iconbox alb element – icon choice the wanted icon – the bubble info text shows you the hex-code

7) To substitute the standard icon of enfold insert this code to your functions.php of your child-theme:

add_filter('avf_default_icons','avia_replace_default_icons', 10, 1);
function avia_replace_default_icons($icons){
$icons['gplus'] =  array( 'font' =>'gplus', 'icon' => 'uf0d5');
return $icons;
}

Thanks

or if you like to have a colored g+ logo
upload a png file like :

and add this to your quick css:

.social_bookmarks_gplus [data-av_icon]::before {
    content: "\00a0\00a0\00a0";
    width: 30px;
    height: 30px;
    background-image: url(/wp-content/uploads/google-plus.png);
    background-size: cover;
    background-repeat: no-repeat;
}

#top #wrap_all .av-social-link-gplus:hover a {
    color: #fff;
    background-color: #eadd4e;
}

background-color on hovering it is your part to declare it