You can customise the footer of your invoice template to add your bank details. The steps to do this are pretty quick and easy, and I'm happy to walk you through how:
In QuickBooks Online (QBO), go to the Settings (gear) icon and select Custom form styles.
Locate the invoice template you're using, then click Edit from the Action column or choose Invoice from the New style dropdown.
Select the Content tab and click the footer (third) section.