Can two separate users have their own check printing settings for separate printers? When I change mine, it messes up my assistant (we don't share a printer)

Hi, @hudsonpsny.

Welcome to the Community. Let me share some information about the printer preferences in QuickBooks Online (QBO). Any changes in the printer settings will stick to the program. Thus separate users won't be able to set up their own printing settings.

I've also attached here an article for future reference. This is for aligning your checks when printing: Align how your checks print. 

Feel free to drop a comment below if you have further questions. I'm just here to help. Have a great day!