How To: Changing the Default Group Settings for a Course
If you wish to apply a default group setting for a course or want to force ever activity in a course to use a specific group setting go to the settings section of your course located in the administration block
Once on the settings page scroll down to the groups section.
From here you can set the group mode for the overall course. It will also allow you to force the group settings to every activity within the course by setting “Force” to yes.