Noticed something today that I have seen before in the past......

Noticed something today that I have seen before in the past... but I don't understand how this is happening... wondered if any one else can inform me..

I noticed a large buyer today on one of the stocks I hold, originally he line wiped the 1.4cents with a $500,000 order, it didn't get entirely filled and left him siting there with the remaining of his order as shown below:



The SP has not fallen back to this price as yet but somehow he managed to change his order and still remained at the top of the que... how is this possible...:



there has been no sell down to the 1.4cents level since his original line wipe... however he managed to change his order and still remained at the top of the que... how is this possible... I have 3 brokers I use, commsec, ANZ and NAB... If I amend a order it puts me to the back of the que... any one here have a broker that allows you to amend a order while still holding position in the que?... genuinely would love some true input on this, IMO this is a game changer for trading... how is this possible?