I want to download the entire general ledger from QB onto Excel, make adjustments, then re-upload onto QB - what is the best way to do this?

It's nice to have you here on the Community page, @grantplumridge.

Exporting transactions from QuickBooks Online (QBO) to Excel and adjusting them or re-uploading to QBO may cause duplicate entries. To make the necessary adjustments and avoid doubling the transactions, you can record a journal entry or modify the previously created transactions.

Before creating an entry, it's highly recommended to consult with a professional accountant to help record and account it accordingly.

For more information about importing and exporting reports, lists, and transactions to and from QuickBooks, you can read these articles:

• Export reports, lists, and more
• Move your lists to QuickBooks Online

If you have any other questions, just leave a comment below and I'll be right here to help you. Cheering you continued success!