I have money on my iTunes but I can't use it because I don't no the answer to my id questions (forgot them) so how do I change them??

If you have a rescue email address (which is not the same thing as an alternate email address) on your account then the steps on this page will give you a reset link on your account : If you forgot the answers to your Apple ID security questions

If you don't have a rescue email address (you won't be able to add one until you can answer your questions) then you will need to contact Support in your country to get the questions reset : Apple ID: Contacting Apple for help with Apple ID account security

When they've been reset (and if you don't already have a rescue email address) you can then use the steps on this page to add a rescue email address for potential future use : Manage your Apple ID primary, rescue, alternate, and notification email addresses

Or, if it's available in your country, you could change to 2-step verification : Frequently asked questions about two-step verification for Apple ID