Are you trying to change data you entered ---like your income, etc? You have to prepare an amended tax return in order to do that. If you only want to change your address, then you need to file a change of address form with the IRS--and perhaps the state----in order to do that. You do not go back to the already filed tax return and change the address you entered on it at the time that you filed.
Or do you need to change the information in your TurboTax account?
Please be clear here about exactly what you are trying to change.
CHANGE OF ADDRESS
UPDATE MY ACCOUNT
have you even filed 2020 because it can no longer be prepared online?
if you just want to alert the IRS to a change of address file form 8822
also, update your address with the USPS if that has not been done already.
You should not make any changes to your tax data file (either online or on your desktop computer). Leave your return exactly as you filed it with the IRS. Only make changes if you need to amend your return to change your income, deductions or credits and pay extra tax or claim an extra refund.
If you need to update your address with the IRS, there is a separate form for that.
If you are preparing a current return and it is importing outdated information from a previous return, you can go back within the current return and correct the information. Don't try and change the previous return.