To update the details on the Form 3922, you would need to edit the sales entered in the investment section. Go through each sale and make the necessary adjustments to correct the form.
Once logged in to TurboTax, on the Tax Home page,
1. Click Review/Edit or Pick up where you left off under the Wages & Income section
2. On the income summary screen, click Add/Edit next to Investments and Savings
3. Click on the brokerage you'd like to edit and then click Review