Read these links please:
About Apple ID security questions - "Learn about Apple ID security questions, including how to set up or change your questions." - https://support.apple.com/HT201363
"If you forgot the answers to your Apple ID security questions" click here --> https://support.apple.com/HT201485
If you see the message, "not enough information" read this link:
Security and your Apple ID - https://support.apple.com/HT201303
"Without proof of your identity via a temporary Support PIN and other carefully selected criteria, Apple Support can't help you perform any actions on your account." Unfortunately the solution they offer using a temporary PIN also requires knowing your security questions answers... <-- I think this is what you are finding. :-/
With that in consideration, if the online option does not resolve the problem I suggest trying to get a personalized response with a chat or telephone call. To talk by telephone: Contact Apple for support and service - Apple Support --> https://support.apple.com/HT201232
For other support options including those if your country does not have telephone support: https://support.apple.com/choose-country-region To chat, choose any topic, (not Apple ID) continue working your way down options until you find one with chat support, then ask to be redirected.
(Note: If your country is not listed, there may be a support option at the end of each region section for "other".)
Apple is encouraging users to use Two Factor Authentication instead of security questions. --> https://support.apple.com/HT204915