Q: I forgot my security questions, need to reset

If you have a rescue email address on your account (an alternate email address is different) then you can use that to reset them : 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 have to contact Support in your country to get the questions reset : Contact Apple for help with Apple ID account security

If your country isn't on that page then try this form and explain and see what they reply with :  https://www.apple.com/pshin/support/itunes/contact.html

When they've been reset, and if you don't already have a rescue email address, you can then add one 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

how do I change my security question when locked

If you've locked your account by having too many guesses at your answers you might be able to re-enable the account yourself : If your Apple ID is locked - Apple Support

For resetting your security questions : If you forgot the answers to your Apple ID security questions - Apple Support