There is support for 7 sets of 3 raidabilities (21 total). If you enable the titlebar for the raid window you'll see a small "S" button in the upper right corner. Click that to open the settings popup. From the settings popup, you can load any of the other sets you've defined. You can also edit abilities while in-game but they don't save on log out.
There are indepth instructions for tweaking your raidabilities in the the
Customizations thread.