What do you mean you just filed 2018? Did you use the Desktop program installed on your computer? Online is ONLY for 2019. So if you used the Online web site you have a big problem. It thinks it was for your 2019 return.
If you actually submitted and filed your 2018 info then you have to wait until the IRS Accepts or Rejects it.. If it Rejects you can change it around to be for 2019 and resend it. BUT if it is Accepted then you need to wait for the IRS to fully process your return and you get the first refund or pay the tax due. Then you can fill out an Amended Return 1040X and change the whole return to be for 2019. So if you have filed DO NOT change or enter anything else into your return until you find out if you have to amend.
Then you still have to file 2018. So post back for more info on all this.
