I answered the age question wrong for a retirement withdrawal. I was over 59.5 years of age when I made the withdrawal

Because form 1099-R accounts for so many situations, when you make a mistake in answering a questions, it's best add the form 1099-R again and then delete your prior entry. To do so, follow the steps below. 

1. Login and click 'Take me to my return'
2. Select the 'Federal Taxes' tab and then click the 'Wages & Income' tab below it (If you have the blue button 'Check for more income' click it and then click 'Skip to see all income')
3. Scroll down to 'Retirement Plans and Social Security' and click the blue hyperlink 'Show more' 
4. Click 'Start' or 'Revisit' next to 'IRA, 401(k), Pension Plan Withdrawals (1099-R)'
5. Next, since you've already entered a form 1099-R, you'll be on a summary screen of your retirement forms entered. Click "+ Add Another 1099-R" to add your form again. You'll have the option to import it or you can simply select "I'll type it in myself." 
6. After, come back into this section and click the blue 'Delete' hyperlink, to the right of the 'Edit' button to delete your form (or vice versa).