Just add a rescue email to your apple.id by going to https://appleid.apple.com/ and click on manage account. Once you have added your rescue email You must verify it by going to your rescue email account. After you have verified it you can go back to apple.com and and click manage account. It should then Ask you to answer your original questions but below it should be a link that sends reset information to your rescue account. Just follow those instructions and you should be able to make new security questions. Hope this helps!