Hi @triptipande
Welcome back to the community forum. I would say this may not be possible i.e. locking the user from editing. However, you can save the first version of their response in a calculate cell using the once() approach as shown in the following example I had done for an exam trial in a different support query.
When the answer is changed at a later time, the original calculation is locked to what was entered first and after the user said OK.
In implementing this on your form, I would suggest adding a calculation question for every question within each section but after the section is completed, that allows the person to change during the administration of the section only and once they click ok, their original choices will be the one on record.
Stephane
