Amending Accepted Return After E-File

My 2020 return has been accepted by the IRS, but I need to amend it. When I filed, I filed I had not received the second stimulus check, but after filing the check arrived via mail. I have followed the instructions to click show, however there is no option in the list to Amend. I need to amend the return to correct the stimulus, and to change the amount of social security withheld (employer sent a corrected form). Please advise how I can Amend.

 

I used the Turbo Tax Online free version to file.