@Im156 A Joint return is only one return combined for the both of you. Why do you need to amend? Did you accidentally file 2 returns?
It's common to end up with multiple accounts. First LOG OUT of whatever TurboTax account you're logged into right now. Then use this TurboTax account recovery website to get a list of user ID's for an email address. Run the tool against any email addresses you may have used
https://myturbotax.intuit.com/account-recovery/
How to amend 2020
https://ttlc.intuit.com/community/amending/help/how-do-i-amend-my-return/00/27439
