add_filter( 'avatar_defaults', 'wpb_new_gravatar' );
function wpb_new_gravatar ($avatar_defaults) {
$myavatar = 'https://valhallatees.co.za/wp-content/uploads/2019/05/valhalla-navy.png';
$avatar_defaults[$myavatar] = "Default Gravatar";
return $avatar_defaults;
} 
