If you double-click on your User Name on the top menu bar, it should take you to your Personal Details page of Your Account. Alternatively, if you single-click on your User Name on that menu bar, a menu should drop down and on that menu you should see Personal Details (other items on that menu will be such things as Signature, Contact Details, Preferences, Avatar, etc.). Does Personal Details not appear for you? Personal Details would be where you can change things like your Custom Title, Status Message, Location, Gender, birthday display, etc.