If you want to revise an order then you can do so using the
Revision Ticket. Right click on the order that you want to revise in the My Bid or My Offer column and the Revision Ticket will be displayed with the order details in it. If you have several working orders at the same price then the details for all of them will be displayed.
To revise the order simply change the price and volume as needed then click the Revise button.
Note that if you wish to retain your order time priority, or queue position, at the exchange then you can only revise the volume of the order down. If you increase the volume of the order, or change the price then you will lose your queue position.
See
Revision Ticket for more information on revising order details.