There are 2 available skins for these forums, "Core" which is the default, and "Curve" which I find easier to read. To change skins go to your profile, and under Modify Profile go to Look and Layout. At the top of the page you should see Current Theme, and a "change" button next to it. Hit the change button and you will be given the option to select 1 of the 2 available skins.
Each skin lets you collapse or expand the header that includes your name at the top of the screen. When it is expanded so that your avatar is visible you also get links to "Show unread posts since last visit." and "Show new replies to your posts." Both of these will be effected by what membergroups you are part of. Membergroups are explained below.