Yes, you can change your Security Questions. Just follow the steps below that would help you out.

1. Tap on the Menu (icon with 3 lines)
2. Tap on User settings
3. Tap on Account Tab
4. Tap on Security Questions
5. Tap on 'Choose your Security Question' and choose the questions you prefer
6. Tap on the grey line below the question to change your answer
7. Tap Submit

You can do the same to update your second Security Question.