I accidentally forgot to reconcile voided checks from two months ago. Is there a way to fix this in Quickbooks? Without having to undo the reconciliation

Yes, there's a way to reconcile those voided checks without undoing your reconciliation, janisc18.

QuickBooks Online has the flexibility to reconcile transactions manually. Since these are voided checks, we don't need to undo the reconciliation.

Instead, we can manually reconcile them through the register. Let me show you how:

1. Click Accounting in the left panel and choose Chart of Accounts.
2. Locate the appropriate account where the voided checks are associated.
3. From the Action column, select View Register (or Account History).
4. Identify the transaction to edit.
5. In the reconcile status column (indicated by a checkmark), repeatedly select the top line of the transaction to change the status of the transaction. Codes indicate the status of the transaction:
   1. C - Cleared
   2. R - Reconciled
   3. Blank - Not cleared or reconciled
6. Hit Save.
   

We can take a look at these resources to help us with reconciling transactions as well as fixing discrepancy issues in QuickBooks Online:

Reconcile an account in QuickBooks Online.

Learn the reconcile workflow in QuickBooks

Feel free to get back to me as I want to make sure everything is taken care of for you, so please let me know how it goes, janisc18. I'll be here to help. Have a good one.