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.
You can't file a 2018 return online. You may be trying to submit 2018 information in the 2019 program. Did you transmit your returns yet or just pay the fee (transmitting is one step after payment).
Do you also need to file 2019 or did you already do that, and if so, how?