The OP, @ddinh, means Form 8949, not 8940. He wants to enter an adjustment in columns (f) and (g), but he has not said what adjustment code he wants to enter.
@ddinh Please answer the following questions.
- What adjustment code do you want to enter in Form 8949 column (f)?
- Are you using TurboTax Online or the CD/Download Desktop TurboTax software?
- What edition of TurboTax are you using (Deluxe, Premier, Premium, etc.)?