After you file

Ok ... in the 2015 program you  do enter NOL in the search box then jump to that section and enter the 2017 NOL carryback amount on the screen that says 2014 carryforward ... this will put the amount on line 21 of the form 1040 as needed. 

Of course, since the 2015 tax year is closed for amended returns you really need to use the form 1045A to get the refund.  I would seek local professional assistance in this matter.