We scheduled an online payment, but then immediately cancelled it. The funds still came out of our account. How do we VOID this transaction to get funds returned?

I'll make sure you'll get the right support in voiding the online payment to get your funds returned to your account, @accounting418. 

Once you've signed up and used the Bill Pay application by Melio, every vendor, bill, or payment will be synced between the two platforms. Since you're unable to find the option to void the canceled payment in QuickBooks Online (QBO), I'd suggest getting in touch with their dedicated support team. They have the tools to check if there are preferences you'll need to enable from their end to void it successfully. This way, your funds will be returned to your account. 

To contact them, select the Help icon on the bill payment screen within the program, and click Start a chat. You can also use the email or phone number on that same page. The screenshot below serves as your visual guide. From there, you'll also get answers to the frequently asked questions about using Melio in QBO. 

Lastly, I recommend visiting this link to learn more about the key benefits, details, app info, and how Melio works with QBO. 

I'm just a comment away if you need anything else. Keep safe always.