Are you on the auto renew Advantage plan? How to cancel
https://ttlc.intuit.com/community/downgrading/help/how-do-i-cancel-my-turbotax-advantage-subscriptio...
Then next year you will need to have the .tax2018 file on your computer to transfer into 2019 online. Post back next year if you need help transferring it.
FYI -
If you used the Desktop program you may not like the online version. It has less features and no Forms Mode. You can only do 1 return. Your return is only saved online so be sure to save both the .tax2018 data file and the pdf file to your computer when you are done. In case you need to amend in the future or if you need a copy to get a loan or something. You might not be able to access your online return when you need a copy.
