Sales matrix without hierarchy

Hi, I am very new to Power BI and I am trying to create a matrix displaying sales totals for different customers. What I want to achieve is something like this:

each record in my dataset is (customer number, customer name, campaign, invoice number, amount, date).

The problem is that when I add the customer number and then the name to "Rows" in the matrix, they will appear in a hierarchy automatically. IS there a way I can define the columns without the hierarchy?