Role renaming
From MoodleDocs
You can rename the roles used in your course. For example, you may wish to rename the Teacher role as "Facilitator", "Tutor" or "Guide". These new role names will appear within the course.
To rename roles in your course, go to Course navigation > Participants > and from the dropdown select Role renaming:
Note also that the site administrator may have changed the names or added new roles. These names will appear and the teacher may rename them.
If you want the word for 'Teacher' to be different in all courses on the site, a site admin can edit the roles of teacher and non-editing teacher in Administration > Site administration > Users > Permissions > Define roles and change the custom full name there.