Welcome to the Community space, @ThinAir.

Let me share an idea on your concern about Printing a single standard check.

The given steps by my colleague above are a way to print checks in bulk, so those checks that the box was ticked as print later will appear on the Print check page. You have to make sure that the check that you like is marked as printed later.

Here's how to print checks:

Before you start, load some blank paper into your printer for your test prints. That way you won’t waste actual checks if you need to fix the check alignment.

1. Select + New.
2. Select Print Checks.
3. Select Add check (make sure to tick the print later box).
4. Select Print Setup.
5. Save and Close
6. After that, tick the box of the check that you want to print.

Here's a photo as your reference:

1. Select your check type, voucher, or standard.
2. Select View Preview and print sample. Then select Print.
3. Follow the on-screen steps to finish printing your sample check.
4. Put the sample print under a blank check. See if they line up correctly.

If it lines up, you’re all set. You’re ready to print on your regular blank checks. 

Additionally, here are some articles that you can read to help you learn how to set up your print settings and how to create and record checks in QuickBooks Online:

• Create and record checks in QuickBooks Online
• Configure your print settings for printing checks in QuickBooks Online

If you need any further assistance with your Printing standard checks, please don't hesitate to let me know by leaving a comment below. I'll be more than happy to help you.