I add the last stimulus payment to this year. and it wont let me change it.

If you are referring to entering your stimulus payments on the Recovery Rebate Credit worksheet, you can review your information to enter or verify your stimulus payments received before filing your return.  Follow the instructions below.

In TurboTax Online, to claim the Recovery Rebate credit please do the following:

1. Sign into your account and continue from where you left off
2. Click on Federal in the left-hand column, then on Federal Review on the top of the screen
3. On the next page titled Let's make sure you got the right stimulus amount, click on Continue
4. Follow the interview (check the figures and make the necessary changes
5. TurboTax will determine whether you are entitled to any additional stimulus
6. Any stimulus amount remaining due to you will show as a credit on line 30 of your form 1040.

Get My Payment - Select the button Get My Payment to see if your information is current based on the payments you did receive.