I forget the security questions

If you forgot the answers to your Apple ID security questions - https://support.apple.com/kb/HT201485

Frequently asked questions about Apple ID - http://support.apple.com/kb/HE37 --> Can I change the answers to the security questions for my Apple ID? --> Yes. You can change the answers to the security questions provided when you originally signed up for your Apple ID. Go to My Apple ID (http://appleid.apple.com/) and click Manage your account.

Kappy's user tip: Some Solutions for Resetting Forgotten Security Questions - https://discussions.apple.com/docs/DOC-4551

KingPenguin 02/2015 post - https://discussions.apple.com/thread/6829577?answerId=27660375022#27660375022

About your Apple ID email addresses - https://support.apple.com/HT201356 - "If you ever forget your security questions, you can use your rescue email address to reset them. If you don't have a rescue email address, you'll need to contact Apple Support for help. We’ll also send any account security-related notifications to your rescue email address. "

Jan 2014 post about contacting Apple to reset security questions - https://discussions.apple.com/thread/5798365?answerId=24543247022#24543247022 and https://discussions.apple.com/thread/5838743?answerId=24671039022#24671039022 and related post, Feb. 2016 - https://discussions.apple.com/thread/7375427?answerId=29465949022#29465949022

If none of the above work, contact iTunes Support at http://www.apple.com/emea/support/itunes/contact/ and follow the instructions to report the issue to the iTunes Store.