I'd like to begin with welcoming you to the Community. I'd be pleased to provide you with some details about adding a memo column to the print check screen.
Adding a memo column on the print checks screen isn't an option for us. However, the memo that you're going to enter upon creating the check will certainly show up on the printed check.
The development team is constantly working to improve the product and appreciates the help of users in bringing things like this to their attention. That said, I'd encourage you to visit our QuickBooks Online Blog to be updated with our latest news and updates including product improvements.