Click on "User CP" at the top, then, to the left, click on "Edit Profile." Then, go down to "Custom User Title," and change it. I'm not sure whether one has to have a specific amount of posts to be able to change the user title, but you may not have a problem, since you already have a considerable amount of posts under your belt, especially for someone who joined earlier this month. Damn, how the hell did you manage to post so much? You almost have as many posts as me, and I've been posting here for almost 6 years.