To place students manually into groups that you choose, the option you’ll select is # of groups -no auto enrollment. You might want to rename the groups, if so please view the following video:
https://www.macvideo.ca/media/Groups+-+Self+Enrol+-+Renaming+a+group/1_ydi2t5rv
Once the Groups are named (if required), you will need to begin to enrol users into groups.
1. In the Groups tool, click on the name of an individual group.
2. Click Enrol Users.
3. From the drop down menu at the top of the screen, select All Groups.
4. Then click on the checkbox to enroll users into the appropriate groups.
5. Click Save when finished.
For more information on how to set up Groups so students self-organize into groups visit: How do I set up Groups for students who are self-organizing into topics I choose?