Hello there, droe.
I can see how convenient it is to have a voided check dated to when the action is taken.
As of now, this option is unavailable in QuickBooks Online. I'd suggest sharing this suggestion with our Developers team.
As a workaround, you can use the Memo field to enter the date when you void the check.
Also, feel free to check this page as your reference in managing your expenses: QuickBooks Articles page.
You can always drop a question in the forum. I'll be around to help you out!