How to clear an uncleared cheque

I'd be pleased to share information about clearing uncleared cheques, @ealingsnuchurch-.

Do not void it since it is from a previous period.  Create a deposit and use the same account used on the uncleared check.  Then, when you reconcile, clear the deposit against the check you want to void.  You'll have to manually check each transaction from your account's register to mark them cleared. 
 
Also, I would encourage you to reconcile your accounts every month. This will help monitor your income and expenses and detect possible errors accordingly. For the detailed steps, please refer to this article: Reconcile an account in QuickBooks Online.

I want to share this article to create a report in QuickBooks Online of checks that haven't cleared yet: Run a report of uncleared checks in QuickBooks Online.

Let me know if you need any help when clearing cheques in QuickBooks. I'd be happy to provide additional guidance when using these features.