Hacked into facebook

Hello,
someone has hacked into my facebook and my email account, i had to change both of the passwords. i changed the password on facebook and the password to my email. I think i know who has hacked me, because they know the answers to my two login security questions on facebook. So i need to change either my login security questions, or i need to change the answers, can you tell me how to do this, so i do not get hacked again.. because i have changed my password, but when they try putting the password they put in, and it doesn't accept it, (because i have changed it), those two security questions will pop up and they know the answer to them, and they will change my password and hack me again, Pleas help. thanks, amber acuff