So I forget my sucirity awnsered and I want to buy a app what can I do

Hello there, RyanBonfield.

The following Knowledge Base article goes over what to do when you don't remember your security questions for your Apple ID:

Apple ID: All about Apple ID security questions

http://support.apple.com/kb/HT5665

Specifically here:

What should I do if I don't remember the answers to my Apple ID security questions?

Try answering them at least once to see if you can get them right, even if you are not sure you remember the answers to your security questions.

If you are confident you can't remember them, try one of the following:

• If you have three security questions and a rescue email address
  

  sign in to My Apple ID and select the Password and Security tab to send an email to your rescue email address to reset your security questions and answers.

• If you have one security question and you know your Apple ID password

  sign in to My Apple ID and select the Password and Security tab to reset your security question.

• If you have one security question, but don't remember your Apple ID password
  

  contact Apple Support for assistance. Learn more about creating a temporary support PIN to help Apple confirm your identity when you contact Apple Support.

Note: If you have forgotten your password and answer your security questions incorrectly too many times in a row, you will be unable to try to answer your security questions for a period of time. During that time you will not be able to reset your password and will not have access to your account.

Thanks for reaching out to Apple Support Communities.

Cheers,

Pedro D.