Good evening, @tom13.
Allow me an opportunity to help you configure your printer settings in a way that works best for your business. Whenever you press Print in QuickBooks Online, the software prepares the information for printing and hands it over to your internet browser to pass on to the physical printer. This means that QBO plays no role in deciding the default device for all printing tasks, and rather this setting must be configured either in the browser or the operating system you're using.
As a brief example, here's how to switch your default printer using Google Chrome:
Change default printer using Chrome
This makes it so every document printed through Google Chrome uses the same selected device. For additional information, check out our guides on troubleshooting printing in Windows or troubleshooting printing in Safari (Mac) to find all the answers you're looking for.
Also, please feel free to keep in touch with me here for all of your QuickBooks needs. Thanks for coming to the Community and have a great day.