I just amended my 2023 tax returns (using TurboTax for both), after efiling it was quickly rejected due to the missing PIN. I have that PIN number now, however, I do not know how to edit the already amended return and resubmit the efile.
A 2023 amended return cannot be e-filed. You have to file it by mail. Only certain tax professionals with professional tax software can e-file past year returns. Your amended 2023 return must be printed, signed and dated in ink, and mailed to the IRS.
Use a mailing service like certified mail so you will know the IRS received it, because you will have a long wait.
Do not expect quick results from amending. It can take four months or more for the IRS to process an amended return.
You can watch for information here:
https://www.irs.gov/Filing/Individuals/Amended-Returns-(Form-1040-X)/Wheres-My-Amended-Return-1