The correction facility is for making all the corrections at a time. You cannot use the correction window separately for each field. It is a one time facility for making corrections in all the required fields. NTA does not guarantee that any request for change in information will be entertained. So it is the best thing to make a note of all the corrections that you need to make when the correction window opens from January 15th to 31st and click on the "Final Submit" only after making all the changes that you want to.