I am knowledgeable of how to find a transaction using its transaction number, @info-wholehealth. Let me give you some ideas and guide you.
Simply use the magnifying glass to look up transactions in QuickBooks Online. Other than the transaction number, you can also enter the date or amount of the transaction you're looking for. See the image below for reference:
If it doesn't show up in the list of results, click on Advanced Search to change the filters and locate the desired data.
Here's how you can use the Advanced Search option: