Thank you for joining the Community. I'd be happy to help share some information on how you can print the invoices with the MFC-7860DW Brother printer.
Any printer can work, as long as it connects to the computer you're using to access QuickBooks Online (QBO). To start, let's make sure that it's set as your default printer.
Open Control Panel.
Go to Printers and Faxes.
Right-click on a printer and then select Set as Default Printer.
Close the Printer and Faxes window.
After that, check if you have the required Adobe version for printing forms with QBO. Once done, I recommend checking this article on how to set up printing alignment for invoices and other sales forms: Set up printing alignment.