Modify my limit price - in detail

To modify an order quantity you may choose to leave the old order up and enter a new order for the difference. This retains the original order's position in the order matching queue.

To modify an order's limit price you must kill the old order and enter a new replacement.

Given sufficient available resources you can put the new order in before killing the old, but this runs a risk of trading both.

Why can't I modify an existing order's price?

You cannot modify an existing order's limit price because you must surrender your position in the order board queue.

Think of it the other way around. It would be unfair if someone else could see you offering a better price, match your price, and in so doing jump ahead of you in execution priority by virtue of being an earlier order. Clearly they must go to the back of the queue at their new price.

The procedure

Step 1. less detail	LOGIN . Bring up your orders from the HISTORY ORDERS screen. Apply filters to see relevant active orders. Click on the order you want to change to display that order's details in the orders panel.
Step 2. less detail	If the order is still active the KILL ORDER button will display. To replace it you must first take the order down from the order board. Press KILL ORDER .
Step 3. less detail	Click the BUY , SELL , or WIZARD tab on the top of the order panel. Re-enter your order from the beginning, applying the new values. Then press the BUY/BID or SELL/OFFER button at the bottom of the order panel, review your order and press CONFIRM at the bottom of your order panel. If you need to remind yourself about entering orders in general go here.