You can edit your tuition amounts from the Education Summary Page, try these steps:

When you are signed into your tax return, you can type 1098-t into the search bar at the top of the page and click on the Jump to 1098-t link to get back to the education section in TurboTax.   You will be taken to the education section but the exact screen you will land on depends on where you left off.  Click through the screens until you get to the Expenses Summary, which will list all students on your return. 

In order to change the tuition amounts, you will need to click on Edit, next to the name of the student on the screen titled Your Education Expenses Summary.  

That will take you to a screen titled Here's Your Education Summary.  From this screen, you can edit the tuition amounts by clicking on Edit next to the name of the school.