HELLO I can't change my birthday

You need to give Apple Support a call and have them reset your security questions: Use this form: Contact Apple for help with Apple ID account security - Apple Support

See the last paragraph in this document:

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

If you can't reset your security questions

If you can't send a reset email, don't have a rescue email address, or can't access email at your rescue email address, call us for help. When you call, you might need to create a temporary support PIN to verify your identity. After you reset your security questions, you might want to update your rescue email address.

If you answer your security questions incorrectly too many times in a row, you temporarily can't access your account. You can try to reset your questions after the waiting period ends