I was voiding / deleting some duplicate expenses and it turns out the ones I voided were matched to bank transactions. How do I re link the 'right' expenses? Thanks

Thanks for posting in the Community, simon10,

Let me get the help you need in matching transactions in QuickBooks Online.

In your case, since you’ve deleted the match transaction instead of the duplicate, what you can do to re-link the correct expense is to match the duplicate transaction again that is on the For Review tab under the Banking page.

Here's what you'll need to do:

1. Click Banking in the left navigation menu and click on the specific bank account in the Banking tab.
2. Go to the For Review tab, then look and click the specific transaction.
3. Select the Find match button.
4. In the Match transaction window, select the specific transaction.
5. Click Save.

That's it! By following the steps above, I'm confident that you'd able to match the correct right expenses.

For additional reference, I've got a great resource that you can check: Add and match downloaded bank transactions [Video].

If there's anything else you need help with, please feel free to visit the Community again. Have a great day!