How do i switch from file by mail to e-file for my 2019 taxes?

You cannot e-file a 2019 return.  E-filing for 2019 closed permanently in October 2020.  The only way to file a 2019 return is by mail.  Print it, sign it ink and mail it in.

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.

Federal and state returns must be in separate envelopes and they are mailed to different addresses.  Read the mailing instructions that print with your tax return carefully so you mail them to the right addresses.

Did you prepare your 2019 return using 2019 software?   The current online program is ONLY for 2020 returns--it cannot be used for a 2019 return.