My first instinct was to say that I would change the fact that I was too trusting with people, and wanted to believe the best in them. Even when they were utterly horrible with me. But then I thought about it, and I realised that those experiences have made me a lot less trusting of people, and more cynical. And honestly, that isn't a whole lot better.
So... no, I don't think I would want to change anything (outside the obvious). I am who I am, scars and all. Some of them I wear with pride, some of them no one ever sees. But at least I know I am me.