I need to go back to adjust my unclaimed tips. how do i get back to that screen to adjust this

Do you mean tips that were not included in your W-2 because you did not report them to your employer? Go back to where you entered your W-2. Click the Revisit or Update button for Wages and Salaries. On the W-2 summary screen click Edit for the W-2 where you entered the tips that you have to adjust. Step through the screens without changing anything, just click Continue, until you get to the screen that says "Let's check for uncommon situations." On that screen, make sure that the box for "Unreported tips" is checked. It should already be checked if you previously entered unreported tips. Then click Continue. The next screen will show the unreported tips that you previously entered, and you can adjust the amounts.