Wrong data base for guest book

The guest book take the data base of other data base book.
Efectevily in the conf.inc.php file it is addressed to the wrong one:
$GB_DB["dbName"] = "guestbook_3";
but when i Change to the right one name, the server do not connect.
I think I have to change pass and user?
How I have to change the:
$GB_DB["user"] = "xxxxxxxxx";
$GB_DB["pass"] = "xxxxxxxxxyyyy";
to get the right data base?
Thanks