"who u want to be"meaning
"WHO" you want to be would mean (a person you know of other than yourself).
"WHAT" you want to be would mean (a chosen profession)... like a Doctor, an Actor, a President, etc...
Other people asked questions on similar topics, check out the answers they received:
Other people asked questions on various topics, and are still waiting for answer. Would be great if you can take a sec and answer them