Hello TB_Michelle66,
It would be my pleasure to help you find transactions using the check or invoice number in QuickBooks Online.
Can you share to me what happens when you search using the transaction numbers? Is it showing results after searching or none? Any details you could add would be appreciated.
Ideally, transactions should show when you use numbers through the search function. Let's isolate the issue by performing some basic troubleshooting.
We can start with logging into your QuickBooks account through a different browser. It will help us determine if the problem is related to your browser.
If you're able to use the search function without any problem, please go back to your regular browser and clear its cache. This process will remove unnecessary information and will start the system in a clean slate.
Please reach out to me here should you need any additional assistance, I'm here to serve you.