i forgot my security questions, how i can set my new security questions

"If you forgot the answers to your Apple ID security questions" click here --> https://support.apple.com/HT201485

If you see the message "not sufficient information" see if at this stage you can still sign up for Two Factor Authentication:

Two-factor authentication for Apple ID --> https://support.apple.com/HT204915

If you cannot resolve the issue by signing up for Two Factor Authentication, "Contact Apple for help with Apple ID account security"; click here --> https://support.apple.com/HT204169