Forms editing is only available in the CD/Download version of TurboTax.
In the Online version, the only way to change your entries is through the interview process.
You’ll need to select Federal in the left pane to make changes to virtually all income, expense, credit, and deduction issues, and these changes will flow over to your state return, as appropriate to your particular state.
You’ll then continue to the state interview, or you can select State in the left pane, to make state-specific entries.