You won't be able to change your profile ID for this forum. See this: https://ttlc.intuit.com/community/help/faqpage/title/howregister_email_verify_not_required
Under How Do I register: Tip: Most people create anonymous names for the sake of privacy and to help them feel more comfortable participating. Be creative, have fun with it, but choose carefully: you can't change your login after you're registered.