Here is how to access your return to make changes:
1. In TurboTax Online, sign into your account.
2. Select Tax Home in the left menu.
3. Scroll down to Your tax returns & documents.
4. Select 2018, and then select Add a State (You're not actually adding a state, this just gets you into the right menu).
5. Once you're in your return you can navigate around as usual.
Once in your return, type ip pin in the search box and click on Find. Click on jump to ip pin.