Oops - I had it backwards. Here is the path.
core/local.config.php
Look for the section below.
define('DBASE_USER', 'xxxxxxxxxxxx');
define('DBASE_PASS', 'xxxxxxxxxxxx');
define('DBASE_NAME', 'xxxxxxxxxxx');
define('DBASE_SERVER', 'localhost');
define('DBASE_TYPE', 'mysql');