I used to not like Justin Bieber, but now I really like him and even want to meet him?

There are a million things that you could tell your parents to explain the sudden change. You could say that you were really moved by his personal story in which he never gave up on his dreams and has fought through all of the criticism that he has received. You could say that you greatly admire the charity work that he has started and it allowed you to give him a second chance. If you watch 'Extreme Home Makeover' then you could say that you say the episode that he was in and his generosity touched you. You could say that hearing the song 'Pray' that he sings made you like him. I honestly didn't like him until I heard that song. Just come up with something that made you give him a second chance.