There is nothing else that so kills the ambitions of a person as criticisms from superiors. I never criticize anyone. I believe in giving a person incentive to work. So I am anxious to praise but loath to find fault. If I like anything, I am hearty in my approbation and lavish in my praise.

Dale Carnegie
Profession: Author
Nationality: American
Some suggestions for you :
That's why encouragement is a much more effective teaching device than punishment.
Emerson said: Every man I meet is my superior in some way. In that, I learn of him.
By criticizing, we do not make lasting changes and often incur resentment.
Try honestly to see things from the other person's point of view.
Taft said: I don't see how I could have done any differently.