How to reset your Apple ID security questions.
Go to the Password & Security section, and click on the link underneath the security questions that says 'Forgot your answers? Send reset security info email to [email]'.
This will generate an automated e-mail that will allow you to reset your security questions.
If that doesn't work...
(If you see a message that says 'There are no products registered to this Apple ID, simply click on 'See all products and services')
Choose 'More Products & Services', then 'Apple ID'.
A new page will open.
Choose 'Other Apple ID Topics', then 'Forgotten Apple ID Security Questions'.
Click the blue 'Continue' button.
Select the contact option that suits your needs best.