Change LDAP

[JoJo_ReloadeD]

Hi, I'm new to these forums, hello everybody

I have to change the LDAP auth from a server, from a external LDAP to the zimbra's internal one.

It's a ZCS 4.x, and it doesn't allow to change in the admin panel. Should I have to upgrade to 5.x ?

Thanks

Edit:

It doest allow to change to internal LDAP, option was on the tool bar...

The question is... changing it from an external one to the internal one will preserve the user passwords or do I have to recreate / migrate them?