Change the default avatar in your comments
If you’re using WordPress comments on your posts (rather than a system like Disqus), anonymous users get assigned a generic silhouette image. If you want to change this up to extend your branding, you can update this default avatar with the following functions.php code:
add_filter( 'avatar_defaults', 'newgravatar' );
function newgravatar ($avatar_defaults) {
$myavatar = get_bloginfo('template_directory') . '/images/gravatar.gif';
$avatar_defaults[$myavatar] = "WPBeginner";
return $avatar_defaults;
}