Option sets are a way to maintain multiple different configurations of CTRA.

CTRA Option Sets

All settings/options you have configured so far are saved under an option set named "Default". But then you notice, that the mana-conserve threshold does also apply when out of raid and you don't like this. Just change them back to 100%, go back here and save the configuration under another name (maybe "No Raid"). Or maybe you're a healer within a healing-group rotation, which is assigned to the sole task of keeping the 4 rogues alive. Just switch the display to "group sorting" and save this under another set-name. The possibilities are endless...