Hello i can't change my security question

You need to ask Apple to reset your security questions. To do this, click here and pick a method; if that page doesn't list one for your country or you're unable to call, fill out and submit this form.

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If you mean that you aren't getting the reset link on the Password & Security section of your account on http://appleid.apple.com then that means you don't have a rescue email address on it (an alternate email address is different), and you won't be able to add one until you can answer your questions - 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 to contact Support : https://www.apple.com/emea/support/itunes/contact.html

When they've been reset you can then 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