The TurboTax online editions are only for tax year 2019. You will need to remove all the 2018 tax data you entered and then enter your 2019 tax data.
To complete and file a 2018 tax return using TurboTax you would need to purchase, download and install on a personal computer one of the 2018 desktop editions from this website - https://turbotax.intuit.com/personal-taxes/past-years-products/
A 2018 tax return can only be printed and mailed, it cannot be e-filed.
