Hi there, Red,

Yes, you can go back to the 2019 version. On another note, once you convert a company file to a newer version of QuickBooks, you can no longer open it in any earlier version. Please use the back up copy you created from QuickBooks 2019.

Then, manually enter the transactions you recently created, or you can import them. Here's an article for a guide in importing transactions: Import and export data in QuickBooks Desktop

We recommend following the troubleshooting steps above to fix any unwanted behavior of the software. 

We are here to help if you have any questions.