updating database-user passwords?

I have just moved from a shared account to a VPS and I need to update all my sql database user passwords to match the config files.

I feel dump that I couldn't find a way to let me look at all the database user passwords and updating them.

I have looked at all the options on myphpadmin and mysql which are offered on cpanel but couldn't find the actual passwords for the database users.

any idea ?

To make this a bit more clear, the database itself created by me (webmaster) and as you know when we create any new database we need to add a user name and a password in which they become db_username and db_password in the config files, this password in the cpanel should be saved somewhere so that we can update it when we need it.

hope it is clear now...

thanks