When I go to Invoicing/Customers and then search for a customer, I get no results. How do i find the transactions for a customer so that i can batch change the category?

There are two ways on how you can find the invoices for a specific customer, julietganschow.

First is through the Sales menu. Here's how:

1. Proceed to the All Sales tab in the Sales menu.
2. Click the drop-down list for Filter and select Invoices under Type, then select the name of the customer in the drop-down list for Customer. 
3. Click Apply.

Second is by running the Transaction List by Customer report. Here's how:

1. Go to the Reports menu and look for Transaction List by Customer under the Sales and customers section.
2. Click Customize in the upper-right hand corner of the report.
3. Click Filter and check the box for Customer.
4. Click the drop-down list and select the name of the customer. 
5. Click Run report. 

However, please take note that QBO does not have a batch action feature for editing transactions. You'll need to open them one at a time and make your changes.

Let me know if you need anything else.