How can I see my client's username?

No, you cannot use your email address as your username. 

Additional Information…

Average Price is a column that can be added to both Classic TWS and Mosaic.

For information on how to add a column, please see How do I add a column to my TWS page?…

Clients may configure the Quantity Columns on a TWS or Mosaic page by clicking on the configure wrench in the upper right of a window and select Configure. As an example, click on the Configure wrench then click on the Order Columns tab and on the right under Available Columns click on…

To add or remove columns from the Orders and/or Trades tab in the BookTrader:

1. Click on the Configure (wrench) icon in the top right corner of the Orders or Trades section
2. Select Configure Order Columns or Configure Trade Columns…