Install the newest version of phpMyAdmin then edit the config.inc.php file at around line 69 to look like this:
$cfg['Servers'][$i]['host'] = 'localhost'; // MySQL hostname or IP address
$cfg['Servers'][$i]['port'] = ''; // MySQL port - leave blank for default port
$cfg['Servers'][$i]['socket'] = ''; // Path to the socket - leave blank for default socket
$cfg['Servers'][$i]['connect_type'] = 'tcp'; // How to connect to MySQL server ('tcp' or 'socket')
$cfg['Servers'][$i]['extension'] = 'mysql'; // The php MySQL extension to use ('mysql' or 'mysqli')
$cfg['Servers'][$i]['compress'] = FALSE; // Use compressed protocol for the MySQL connection
// (requires PHP >= 4.3.0)
$cfg['Servers'][$i]['controluser'] = 'admin'; // MySQL control user settings
// (this user must have read-only
$cfg['Servers'][$i]['controlpass'] = 'password'; // access to the "mysql/user" - use Plesk login password
// and "mysql/db" tables).
// The controluser is also
// used for all relational
// features (pmadb)
$cfg['Servers'][$i]['auth_type'] = 'http'; // Authentication method (config, http or cookie based)?
$cfg['Servers'][$i]['user'] = 'root'; // MySQL user
$cfg['Servers'][$i]['password'] = 'root_password'; // MySQL password (only needed
// with 'config' auth_type)