Most likely this is in your bill layout. In the expense section you are probably set to summarize by expense code. You can change this to itemize by going to your bill layout and click on Section > Configure Layout Sections. Then click on Expense Charges from Slips and click on Options. Make sure it is set to itemize.

Note that any changes will apply to all clients that use this invoice so you may want to make a copy of the bill layout. Make the change on the copy and set that as the bill layout for this client.

If it is not the bill layout setting then another possibility is replacement slips. This would be found under slips.