how do I reset my security questions

Sign into your Apple ID account (https://appleid.apple.com/#!&page=signin) and reset them there. But, if I were you, when there, I would opt to use two-factor authentication. It provides much better security than security questions. And, if you chose to use it, you'll never have to do anything with security questions again.

If you know the answers.

Apple ID security questions.    

If you are being told there isn't enough information to reset them, contact Apple ID Support.

If you don't know the answers, if the steps in the article below don’t work, contact Apple ID Support, although I’m not sure they will be able to help. 

Apple ID - If you forgot the answers to your Apple ID security questions.      

From the article below. 

Without proof of your identity via security questions and other carefully selected criteria, Apple Support can't help you reset a password or perform any other actions on your account. These policies are audited and reviewed on a regular basis.

Security and your Apple ID.    

Apple ID - Official Apple Support.    

Contact Apple for help with Apple ID account security - Apple Support.   (Link doesn't always load)  

Get Support    Work through the screens to get a chat option. 

Apple Support schedule phone call

https://twitter.com/AppleSupport