Thanks for joining the thread, @WM280. 

Although this feature hasn't been added yet in QuickBooks Online (QBO), I can suggest a couple of workarounds to customize checks and add your company logo.

As of posting, we can only choose the type of checks to print either Voucher or Standard in QBO. However, it's possible to add your customizations from the checks that you order from Intuit. Here's how: 

1. Sign in to intuitmarket.intuit.com/signin using your QBO account.
2. From My Account, choose Customization Options.
3. Add Customization information or select Add new logo.
4. Follow the onscreen steps.

If you choose to add your logo, here are the things to keep in mind:

• Ensure that the logo file size is less than 5 MB.
• The height of the logo image, in relation to the dpi (dots per inch), should be at least one inch. Anything smaller than that may lose printing quality. If you use a bitmap image, make sure it is at least 600 X 600 pixels.
• Logo color for checks, envelopes (except #10 envelopes), and forms must be black and white. If you'd like a color logo on your checks, you can find their contact details on the top-right corner of the webpage: Small Business Supplies from Intuit Market. 
• Once you have successfully uploaded your logo and placed your order, you'll be able to use the logo on other customized products. Logos that are uploaded, but not used to place an order, will be available for 90 days from the date of upload.

Alternatively, if you want to add your customizations within QBO, consider finding a third-party app on the Find apps page. You can follow these steps: 

1. In your QBO account, go to Apps.
2. Select Find apps.
3. Search for keywords related to printing checks.

Nevertheless, I understand that the software must accommodate various business needs. I'd still encourage sending your feedback to our Product Engineer to implement the check customization feature in future updates. You can also track feature requests through this link: Customer Feedback for QuickBooks Online. Here's how you can add your own feedback:

1. Go to the Gear icon.
2. Select Feedback.
3. Enter your comments or product suggestions.

After customizing your checks, let me add this article as a reference in printing your checks in QBO: Print a check in QuickBooks Online. 

We'll be here in the Community if you have further concerns about customizing or printing checks in QBO. We'll do our best to assist.