TurboTax has no ability to put the word "ROLLOVER" on line 3b. Did you mean line 5b, not 3b? The word "ROLLOVER on line 5b means that you reported a rollover from an employer plan.
Nothing on a 2021 tax return changes a 2020 tax return.
You haven't mentioned anything that suggests that there is something wrong with the 2020 tax return. Why do you think that the 2020 tax return needs to be amended?
In 2021, Form 8915-F replaces Form 8915-E and is where the calculation will be done to include in income another $20,000 of the 2020 Coronavirus-Related Distribution.
