how can i change?

I used to do this exact same thing. Start off small. Go on online shopping websites like target or kohls and browse through the clothes. pick the things you like best, try to not think of types of clothes or people just look at everything. Then try it with music and tv shows. if you go on instagram or if you flip through the magazines, look at which celebrities you like the most. see which ones you have the most in common with based off looking at those clothes and music and stuff. don't just compare yourself with one celebrity, look at several. maybe you like the same clothes as justin timberlake but you like the same tv shows as selena gomez. Your mind might start to think that you want to be like them but you will realize that you are already like them. you just have to determine what you like in different categories and little by little you will become yourself.

You dont have to change. Just be yourself.

This site has loads of articles on just what you are asking. It also has a section where you can take tests to learn more about yourself.
http://lonerwolf.com/