See the FAQ at the following link for instructions to amend 2015, 2016, and 2017 tax returns that you filed with TurboTax.
https://ttlc.intuit.com/questions/1894381-how-to-amend-change-or-correct-a-return-you-already-filed
An amended return (Form 1040X) cannot be e-filed. You have to print it, sign it, and file it by mail. Mail each year in a separate envelope. It takes the IRS up to 16 weeks to process an amended return.
