First of all, thank you for your quick responce!
Secondly, about that specific feedback, I went in the "permissions" page and there is the "Activity: Feedback" in which there is a subcategory named "Comlpete a feedback" and there, only "student" is checked by default!
Therefore, when I delete "students" and I add "instructors" in "complete a feedback", nothing has changed! When i log in as student, i see the feedback but when i log in as instructor i cannot see the feedback!
So, in "feedback" >> feedback administration >> Permissions >> ...and then??
Please, can you telll me exactly what do I have to change in "permissions"?
Thank you Emma.