You may file an amended return from before 2015; however, it is likely that the IRS will not accept payment even if they change the account.  You would need to contact Social Security on how that would affect your case.  Regardless, 2014 can no longer be filed through TurboTax.

However, if you needed to amend the 2015 and 2016 returns you may do so.  You will want to mail in the 2015 return before April 15 to guarantee that the amendment adjusts the return before the statute of limitations has expired if it is necessary that the payment for the change also be credited to your account.

The following FAQ provides instructions on how to prepare amended returns for 2015, 2016 (and 2017 and 2018 as well).  Click the embedded link for the year you need to amend:  https://ttlc.intuit.com/replies/3288565

I filed my 2014 taxes in 2016 though, so I still have time then? And I can't use Turbotax to complete the 1040X form? I have the 2014 version installed on my computer. I know it has to be mailed.

We can't provide you the 2014 software anymore.  If you still have access to your 2014 program, you might be able to prepare the amended return through it.  You definitely can prepare 2015 and 2016 amended returns with TurboTax.  The 2015 program is available until April 15th.