Hi there, marylou! 

I'd be glad to help you with this. 

You can use the Advanced Search feature in QuickBooks Online for this. Here's how: 

1. Click on the magnifying glass at the top center on your home page.
2. Click on the Advanced Search hyperlink. Filter your search by selecting Invoices, Memo, and Contains or Equals. 
3. Enter the memo you're looking for in the field and click on the blue Search button. You can also click on Add Filter to filter the dates.

I've attached screenshots below of how it looks. 

Please let me know if there's anything else that you need or if you're referring to something else.