The Shifting Destination
macOS tries to anticipate your printing needs based on your physical location and recent behavior. By default, it employs a feature that automatically changes your “Default Printer” to whichever printer you used last on your current network. While helpful if you roam between different offices with different hardware, it is a nightmare in a standard office or home setup. If you occasionally print a shipping label to a specialized Dymo printer, macOS will automatically set that tiny label maker as your default. The next time you try to print a 10-page text document, it will erroneously try to squeeze it onto postage stamps.
Locking Your Preferred Printer
To ensure your documents always go to the correct hardware and stop macOS from automatically changing the default printer based on your last action, you must lock the default device in the system settings.
Click the Apple logo in the extreme top-left corner of your screen and select System Settings. Scroll down the left-hand navigation sidebar and click on Printers & Scanners. In the main right-hand panel, scroll down past the list of installed devices. Look for the dropdown menu explicitly labelled Default printer. By default, this is likely set to “Last Used Printer.” Click this dropdown menu and select the specific name of your primary, everyday printer (e.g., “HP LaserJet Pro”). macOS will now permanently lock onto this specific device, regardless of which other printers you occasionally use.