If you need to change advisors, you can pick out another advisor with whom you'd like to work. Ideally, you will pick someone in your field of interest, from whom you have taken one or more classes, with whom you have spoken with outside of class and who has a communication style/personality that meshes with you.
Ask the faculty member if they would be willing to advise you. If they are willing, fill out and print the Request to Change Advisors form on the Registrar's web site under Forms for Students. You can also fill out a form in the Registrar's office (lower level of Towers Hall). Your new advisor must sign the form before you can turn it in. If you do not know who you would like as your new advisor, simply fill out the Request to Change Advisors form and request to be reassigned to a new advisor.