Hello,
You can use the code below to show full name instead of username. Here is the article I got the snippet code from. I would recommend using a plugin like?Code Snippets?to add the code to your site: https://www.ads-software.com/plugins/code-snippets/
add_action ('admin_head','make_display_name_f_name_last_name');
function make_display_name_f_name_last_name(){
$users = get_users(array('fields'=>'all'));
foreach($users as $user){
$user = get_userdata($user->ID);
$display_name = $user->first_name . " " . $user->last_name;
if($display_name!=' ') wp_update_user( array ('ID' => $user->ID, 'display_name' => $display_name) );
else wp_update_user( array ('ID' => $user->ID, 'display_name' => $user->display_login) );
if($user->display_name == '')
wp_update_user( array ('ID' => $user->ID, 'display_name' => $user->display_login) );
}
}