If the steps in the article below don’t work, contact Apple ID Support, although I’m not sure they will help. There have been posts that state Apple ID Support will no longer help reset security questions.
Apple ID - If you forgot the answers to your Apple ID security questions
Enter your Apple (iCloud) ID and click Forgot Password.
Apple ID - Manage
Apple ID – Forgot Password
Apple ID Support
Apple ID Support (2)
Apple Support by e-mail or chat Work through the screens to get a chat option. You may need to pick a problem that is slightly different than yours to get a chat option.
Apple Support using Twitter
Or fill out and submit this form. The form is for iTunes, but it will get passed to the ID Support section.
If necessary, If you are the original owner, take the device, the original purchase receipt with the serial number, and a photo ID to the nearest Apple Store.
Genius Bar Reservation US
or contact Apple ID Support. They will need to see the original purchase receipt/paperwork also.
Apple ID Support
Apple ID Support (2)
Apple Support by e-mail or chat Select your device, Battery, Power and Charging, then Power adapter not working to get a chat option.
Apple Support using Twitter
Or fill out and submit this form.