CALL the apple support team to reset/update them (security questions)..
don't worry, they are very polite and friendly.. =))
all u need to do is verify their questions..
(1) make sure you don't signed out of your apple ID;
(2) prepare you apple device’s serial number;
(3) be sure you are connected to the internet, so that u can help the speed up the "verifying" process..
it only took less than 20minutes to have my security questions reset without losing the balance in my apple ID ^__^
hope this helps.. merry christmas y'all ~.~