I do not think people should change themselves in order to impress someone unless you are doing something important like making a first impression. If your not doing something important, most of the time in school its not necessary. changing can be considered wearing different cloths speaking different or even changing your personality.
You should change yourself when you are meeting somebody important,or going to church, or something like that.
It would not be important to change yourself because what somebody says in school or at the store because you are most likely not going to be doing anything or seeing any body that important.
The End