Client invoices

[tgstudio]

For the second time I have had a client request to be more specific on what I worked on in their invoice. I had assumed that the information I placed in the "Memo" field in the time tracker would appear on the client's invoice. Apparently not. They state that only the project number and hours appear. Is there anything to do to rectify this? Or is there something on the client's end that they can do?