Do the agi change once you do an amendment? And how can I find out my agi?

The IRS requires your 2019 AGI to verify your identity for e-filing. If you're paper-filing your return, you won't need your AGI because those are manually processed.

See the information here for steps to correct your AGI on your 2020 tax return. 

If you need assistance on locating your 2019 tax return, please see the following TurboTax FAQ for more information:

https://ttlc.intuit.com/community/prior-year-return/help/how-do-i-access-my-prior-year-return/00/27010

efile with the AGI from original return.

File with other tax software and your AGI rejected with TurboTax will be accepted.