Each Notification Services instance has one database, which can consist of multiple filegroups. Defining these filegroups is optional.
If you define filegroups, one filegroup must be named PRIMARY. You can have additional filegroups to group additional data files together for administrative, data allocation, and placement purposes. For more information about files and filegroups, see Understanding Files and Filegroups.
If you want to alter the instance database after creating the instance, use the Microsoft SQL Server tools, such as SQL Server Management Studio.