How do I become a mature guy in office that girls will actually like ? Looks don't matter anymore. How to not be called childish anymore ??!?

I am 21 years old and work in office. I don't know my identity at all. I keep changing according to whether people will look me or not. I sometimes act nicely sometimes very rude. I generally don't care about others feelings at all . Especially the way I treat girls. I keep making fun of them and also I flirt with some of them by calling them pretty and giving them other compliments but I don't think they like my attitude because I come off as rude . Many girls think I'm good looking , not hot but good looking and they have told me this as well. But this has never helped me get any special attention. I don't see girls coming to my desk to talk to me without me calling them . How to become good friends with girls ? I also keep comparing myself. Suppose a girl goes to another guys desk and talks to them I keep asking that girl why she doesn't come to my desk. Do girls like this comparison ? Does it bother them. Some of them say I am immature and act childish sometimes. How do I change this and become a guy that girls actually like because they barely care about looks now a days.