I find it interesting how you can print a logo on an invoice, but you can't print a graphic signature on a check.  This is a fundamental need, and I see that it has been complained about now for several years. {Updated 7/15 - I spoke to our attorney about this.  He thinks that QBO won't allow a digital signature because it isn't technically being placed at "my" location.  They would be placing the signature on at their location and then sending it to me to print, and that may not be legal}

To anyone who wants to know how I dealt with this.  I printed all my checks to PDF (after going through the spacing setup for my check stock).  And then opened the resulting PDF in Acrobat, and applied my signature to each page.  I turned on view ruler and grid.  Then "stamped" the page at 5.5" in from the left, and 2.75" down from the top with a custom stamp I created using a JPG of my signature.

{Also updated 7/15 - Found a better way of consistently printing the "digital image of an ink signature" onto the checks using Adobe Acrobat's WATERMARK feature.  I think you need Acrobat Pro, or a similar PDF editor which allows for adding a watermark to the front of a PDF page.

Create checks as one PDF file.  Save the file.  Then under Pages/Edit Page Design/Watermark click on "Add Watermark".  Under Source, select File and then Browse for your PDF image of your signature.  Set Absolute Scale to 100% (depending upon the size of your digital sig.  This may need to be adjusted), Opacity to 100%, Appear on top of page, and if you use the Intuit pre-printed 3-part checks, the Position is Vertical 2.4 inches from Top and Horizontal Distance 5.75 inches from Left.

Use the Preview Page to confirm that the watermark will be on every page.  Click on Save Settings at the top and give it a name.  Then do a test print on one check.  If the signature is too large or small, adjust the Absolute Scale.  If it is too far up or down, adjust the vertical distance accordingly, and the same for horizontal if too far left/right.  Remember to Save again, print again, rinse and repeat until it's perfect.  Then you won't have to deal with this issue ever again.  Just print your checks from QBO to a PDF, and then apply the saved watermark.  Then print on the check stock. - end of edit 7/15}

Then I printed them all out on check stock.

My 2 cents.