Redmine

I've configurated redmine to use the first time LDAP to validate User and pass, after that redmine saves a local file to futures validations, but It isn't useful because if the user changes his LDAP pass redmine doesn't know about it.

I want redmine always uses LDAP to validate users. If you can help me how to modify redmine to do that.

It's urgent to know it to me

Thanks!