Configuring the default configuration profile for Profile Manager

Hello folks,

I would like to edit the default configuration profile served by Profile Manger. As far as I understand the only thing I can configure from the Server.app is the name of the profile. The settings for the different services provided by the server (such Mail, Messages, etc.) are automatically chosen by Server.app. When logging as an administrator on the Profile Manager webapp, I can go to "Groups", choose "Everyone", go to "Settings" to review the different payloads. However, almost none of the settings are editable. You can read "This payload is configured using the Server app" on the top of the various panels.

So my question is: How do you use Server to tweek those payloads? Can this be done using the serveradmin command line tool?

Thank you very much for your help.

Regards