TurboTax automatically calculates the amount for the 4th quarter. It does not change on your screen, but on the form, the income that is remaining shows on column d of form 2210 page 3.
If you look at you refund you will likely see a change as you enter the numbers. If you front load the numbers (add the majority of the income to the 1st quarter) you will likely see your refund drop. When you lower that amount your refund will increase.
You can look at line 38 of your 1040 for your estimated tax penalty. If you are using TurboTax Online, you can see your 1040 form by selecting Tax Tools>>Tools >>View Tax Summary>>Preview My 1040.