A default printer by definition is the printer used unless an alternate device is explicitly selected. At least that’s the way it should work, and has worked in every version of Windows until Win 10. Now though the “default” settings for the “default” printer is to let Windows manage it, which means Windows will automatically change your default printer to the last used printer. I can’t imagine the tortured logic that led to this setting, nor can I imagine the number of print jobs that will be misdirected in corporate America as a result.
Thankfully, unlike so many Win 10 settings that are held in obscure databases, this one is a simple registry setting:
Set to 1 and you’ll have the old behavior back, where your default printer really is a proper default – and stays that way.