Gradebook

In the online manu of Moodle it said,

You can also choose whether a teacher should have editing rights on the course. Non-editing teachers could be thought of as course tutors. They are:

1. not able to change the structure of the course
2. not able to enroll or unenroll students
3. able to grade
4. able to facilitate within activities

When assigned to a group, they are only able to perform task 3 and 4 with that group.

I followed the instruction, created a teacher, disable her Editor status, assign her to one of the three groups within a course.  But I found out she can still edit other group student's grade.  Is that because other group don't have a teacher?  Or did I group the teacher incorrectly?