You cannot edit the Organization Default Attendance Scheme, but you can edit an attendance scheme that you have created.
Editing an Attendance Scheme
- Click on Course Activities > Attendance.
- Click on the Attendance Schemes screen.
- Click the dropdown arrow next to the scheme and choose Edit Scheme.
- Notice the editable fields identified below.
- Make your desired changes.
- Click Save, Close.
See also Creating an Attendance Scheme.