Do I have to download software to amend the taxes?

[DoninGA]

If you are referring to amending a 2024 or earlier return completing using the TurboTax online editions, then yes you will need to download the tax data file from your online account.  And you will need to purchase and download the desktop software to install on personal computer.  Only prior tax years, 2024, 2023 and 2022 can be amending using TurboTax.

See this TurboTax support FAQ for amending a prior year tax return - https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-return/amend-change-correct-return-a...