You changed your opinion on someone

Nowadays it's hard to have the same opinion on people because of the changes they make for the society to like them.
There are a few cases in which you keep the same opinion on someone from the very beginning.
I have changed my opinion on someone a lot, but there where some cases in which my first opinion was a bad one, but later i realised the person was actually very nice.
There are some people that are influenced by the first impression and i don't agree with this because it can be a mistake.
Recently i have changed my opinion on a person that "i have known" for 10 years. She was my very first best friend and we kept talking until i was 12, when she left to England for one year and when she came back she was another person who i didn't want to meet
Even though this creats disappointment, we shouldn't be discouraged. In fact, we should hope that the opinion we have on some people we know should remain tha same.