After you file

You probably can't update the 2019 program.  Did you still have it installed from 2020?  You can't install or update 2019 anymore at all.  It is unsupported.  They only support the last 3 years.  You would have to do the amended return by hand.  Here's one

https://www.irs.gov/pub/irs-prior/f1040x--2020.pdf