Yes, you can still make changes. You can return to any of the sections in the TurboTax program and make changes since the tax return has not be filed.
To make changes before filing:
1. Sign In to TurboTax Online
2. Click "My TurboTax" menu
3. Press "Visit My Tax Timeline"
4. Under the "SOME THINGS YOU CAN DO" heading, choose "Add a state" (you're not really adding a state, this allows you to get back into your return).
5. You may now make the corrections to your tax return.