In order to amend a previous years' return, that was filed using TurboTax Online:
When you first open your return and see "let's keep working on your taxes", scroll down to the section "Your tax returns and documents". If you prepared your 2023 tax return in TurboTax, in the same account, you should see "2023" listed among the documents you can select to view. If you used a different TurboTax account for 2023, you would need to log in to that account to view your return. See this help article for more information.
See this help article for filing nonresident returns. You would need to change information in the Federal return, in the Personal Info / My Info section.