When I amend the return, Sprintax generated both 1040-X and a new 1040-NR, do i need to sign on both and physically mail to IRS? Or only the 1040-X is needed? Or do I need to mail the original 1040-NR not the new one? And they generate 1040-X with watermark "copy", which I don't think can be mailed to IRS
