Once your assessment is `Under Review`, you'll be prevented from making changes directly to your answers, and you will see a grey titlebar indicating that. From this point on in the verification process, you will need to make a request for changes to be made to your assessment.
Even though the questions Answers are read-only, comments can still be made underneath each of your Answers, so that you can clarify your answers, or request and Evaluation Analyst to change an answer.