Hi Nidhi,
I am forwarding your query to the support team at NPTEL. Sorry for the delay in seeing this. As your peer Deepti had identified, some of the fields may not be changeable after initial entry. The usual practice is that an error form is created where you can mention the fields that you need to edit. What will help the support team in giving you a detailed reply is a screenshot of what you are trying to do and the exact list of fields that you are trying to change.
Hi Support team,
Kindly look into the query raised by the learner regarding exam form. You can respond back to this email (reply All) and the same will be posted in the discussion forum of the course and many other learners will be able to get the benefit.