Look at

http://manpages.ubuntu.com/manpages/zesty/man5/smb.conf.5.html

When you would not use a smb.conf and edit under Windows

REGISTRY-BASED CONFIGURATION

       Starting with Samba version 3.2.0, the capability to store Samba
       configuration in the registry is available. The configuration is stored
       in the registry key HKLM\Software\Samba\smbconf. There are two levels
       of registry configuration:

        1. Share definitions stored in registry are used. This is triggered by
           setting the global parameter registry shares to “yes” in smb.conf.

           The registry shares are loaded not at startup but on demand at
           runtime by smbd. Shares defined in smb.conf take priority over
           shares of the same name defined in registry.

        2. Global smb.conf options stored in registry are used. This can be
           activated in two different ways:

           Firstly, a registry only configuration is triggered by setting
           config backend = registry in the [global] section of smb.conf. This
           resets everything that has been read from config files to this
           point and reads the content of the global configuration section
           from the registry. This is the recommended method of using registry
           based configuration.

           Secondly, a mixed configuration can be activated by a special new
           meaning of the parameter include = registry in the [global] section
           of smb.conf. This reads the global options from registry with the
           same priorities as for an include of a text file. This may be
           especially useful in cases where an initial configuration is needed
           to access the registry.

           Activation of global registry options automatically activates
           registry shares. So in the registry only case, shares are loaded on
           demand only.

       Note: To make registry-based configurations foolproof at least to a
       certain extent, the use of lock directory and config backend inside the
       registry configuration has been disabled: Especially by changing the
       lock directory inside the registry configuration, one would create a
       broken setup where the daemons do not see the configuration they loaded
       once it is active.

       The registry configuration can be accessed with tools like regedit or
       net (rpc) registry in the key HKLM\Software\Samba\smbconf. More
       conveniently, the conf subcommand of the net(8) utility offers a
       dedicated interface to read and write the registry based configuration
       locally, i.e. directly accessing the database file, circumventing the