I tried following the steps above but it doesn’t work on the latest enfold theme. I already put this code in my functions.php:

add_filter( 'avf_google_heading_font',  'avia_add_heading_font');
function avia_add_heading_font($fonts)
{
$fonts['Coustard'] = 'Coustard:400,900';
return $fonts;
}

add_filter( 'avf_google_content_font',  'avia_add_content_font');
function avia_add_content_font($fonts)
{
$fonts['Coustard'] = 'Coustard:400,900';
return $fonts;
}

And added this to custom CSS:

font-weight: 900;

but it doesn’t work. In fact when I do “view page source,” I still get this:

<link rel='stylesheet' id='avia-google-webfont' href='//fonts.googleapis.com/css?family=Coustard|Droid+Sans' type='text/css' media='all'/> 
<link rel='stylesheet' id='open-sans-css'  href='//fonts.googleapis.com/css?family=Open+Sans%3A300italic%2C400italic%2C600italic%2C300%2C400%2C600&subset=latin%2Clatin-ext&ver=3.9.2' type='text/css' media='all' />

How do I fix this?