If you're using the default actionbars, you need to find the keybind section that says MultiActionBarX.
Bind the first button of each until you've identified the one you have showing, then proceed to bind the rest in that section.
If you're using an actionbar mod like Bongos2 or Bartender you'll have to look for its own section.
myBindings helps bring some sanity to the keybinding interface but you'll still need to identify your actionbar.
http://addons.us.to/addon/mybindings2