How can i find an invoice by invoice number?

Hi dianenguyen,

Welcome back to the Community. QuickBooks Online enables you to get your work done faster with the help of the powerful features included in the program. I'll be happy to show you how to search for invoices using invoice numbers.

In order to do this, click on the Magnifying glass at the top right of your account > once the search drop-down appears, click on the blue link that says Advanced Search > on the search filter, select Invoice, and specifically filter it to show Invoice numbers. From here you can enter your invoice number and locate your invoices with ease. 

I encourage you to try this out and let me know how you make out. I'll be one message away in case you need additional support.