You can view agent commissions in the Reports tab here:
Scroll down to the Agent Commission report and select the date range to run the report. You can either view the report or download it in CSV.
The Agent column in the report shows the Agent Code indicating who booked the reservation.
Editing Agent Codes for Existing Bookings
When viewing existing bookings, the Agent Code will indicate who made the reservation. Once a reservation has been made, the agent code cannot be changed except by admin users.