I went on your sight to file 2018 taxes and realized after it was done it was filed for 2019 I made a lot less money in 2019 than I did in 2018

Oh no.... so you e-filed it with the wrong income information on it?  The online software is ONLY for a 2019 return.  

Did you really click that big orange button that said “Transmit my return now?”  If you did that, you cannot do anything to fix it yet.  The IRS will begin to accept/reject 2019 returns on January 27.  You have to wait for the email that tells you if your return was accepted or rejected.

Filing before you have all of your information causes you a lot of aggravation that could be avoided if you just wait until you have everything first and then take your time preparing your return so you do not mess it up because of a rush to get a refund.

You cannot change or add anything on the return that you just e-filed, nor can you stop it.  It is too late, just like when you put an envelope in a US mailbox

If you left out a W-2, or a dependent, or a 1099 etc…DO NOT change your return while it is pending.  The changes will go nowhere.

Now you have to wait until the IRS either rejects or accepts your return.  If your return is rejected, you will be able to go into your account and make the necessary changes to your tax return and re-submit your return.

 If the IRS accepts your return, however, then you have to wait longer until it has been fully processed and you have received your refund.  THEN you can prepare an amended tax return and mail it in. You have to be able to work from that return exactly the way it was when it was e-filed originally.  You will need to use a form called a 1040X. You cannot e-file an amended return.  They have to be mailed, and it takes at least 2-4 months for the IRS to process an amended return.  Meanwhile, DO NOT go in and start changing anything on your return in the system, or you will make a mess for yourself.  Sit tight and wait until you see what the IRS does with the return you just e-filed

And as for preparing a 2018 return:

Online preparation and e-filing for 2018 is permanently closed.

To file a return for a prior tax year

If you need to prepare a return for 2016, 2017, or 2018 you can purchase and download desktop software to do it, then print, sign,  and mail the return(s)

https://turbotax.intuit.com/personal-taxes/past-years-products/

Remember to prepare your state return as well—if you live in a state that has a state income tax.

When you mail a tax return, you need to attach any documents showing tax withheld, such as your W-2’s or any 1099’s.  Use a mailing service that will track it, such as UPS or certified mail so you will know the IRS/state received the return.

Note:  The desktop software you need to prepare the prior year return must be installed/downloaded to a full PC or Mac.  It cannot be used on a mobile device.