[Samba] LDAP bindpw password

[shacky]

Hi.

I'm using Samba 4 on two Zentyal servers as Domain Controller and now
I have to authenticate some services to it (Apache and PAM in
particular).
The LDAP integration asks me for a LDAP bind password, but I cannot
find out where it is on Zentyal.
Is there a way to check (or change it) directly on Samba 4?
Or is it preferable to authenticate against Active Directory or Kerberos?

Thank you very much for your help!
Bye