Management of security questions in AppleID authentication
You can go to iforgot.apple.com and then enter your Apple ID email address and then the captcha code there. Then choose continue and reset security questions. Next you choose how you want to reset it (get an email with a link or enter the password). Then you can change the security questions.

Apple Support can reset the password for you. All you need to do is to get verified. You need to attempt to sign in to the Apple ID site. When it asks for your security questions there is an option there that says Get Support PIN. Apple Support needs that PIN as 1 way to verify you. Then all they need next is one of the following: 


At least 1 correct security question
Text you a code to your iPhone or the phone number 
Enter in some of your credit card info that is on file. 


After that they can reset the questions.

Best of luck.