How to prompt user login and password in phpmyadmin

Edit config.inc.php
and the exact line is :

$cfg['Servers'][$i]['auth_type'] = 'http'; // Authentication method (config, http or cookie based)
$cfg['Servers'][$i]['user'] = 'root';
$cfg['Servers'][$i]['password'] = '';

Change original auth_type "tcp" to "http".