How to change thumbs size and aspect ratio

Add the following code to the functions.php of your child theme. If you do not have a child theme then please see here: How to Create a Child Theme

function tifd_feedzy_thumb_aspect_ratio( $sizes, $feedURL ) {
    $sizes = array( 
        'width' => $sizes['width'] * (16/9), 
        'height' => $sizes['height']
    );
    return $sizes;
}
add_filter( 'feedzy_thumb_sizes', 'tifd_feedzy_thumb_aspect_ratio', 10, 2 );