To change your security questions, please follow the 'Forgot / Reset Password' steps. For details, please refer steps in the link below:
I forgot my password - How do I reset it?
Which number will I get an OTP on if my numbers are different in trading and DP?
I did not receive any OTP while resetting my password
Are Neo mobile app and Nest logins different?
How do I change my Nest login security questions?