You should go to a tax professional that is EXPERIENCED with Nonresident Aliens.
<a rel="nofollow" target="_blank" href="
http://taxexperts.naea.org/">http://taxexperts.naea.org/</a>
(1) Your 2015 tax return is wrong, because TurboTax is not able to do Nonresident Alien tax returns, and you were not "Single". The tax professional can help you to correct those mistakes.
(2) For 2016, you are also probably a Nonresident Alien (depending on the exact dates of being in the US, you could be a Resident, but you are probably a Nonresident), which TurboTax can not do.
Again, if you are just filling out a W-4 to give to your employer, yes, you can put "Single". For for doing your tax return (and correcting your 2015 tax return), you should go to a tax professional.
