Sure can RT - from your portfolio page (your home page) - find the company where you have an order in the system that you want to change (tip: it will be at the top of your portfolio - all unfilled orders are automatically listed at the top of your portfolio here) - then click on the circle with the plus sign in it (to the right, but to the left of the star symbol) - I think if you have a current order in play and it can be changed that circle (with the plus sign in it) will be yellow, otherwise it's grey (or black). That circle with the plus sign in it is the shortcut for placing, editing or cancelling orders. Once the pop-up window opens, follow the prompts to choose what you want to change. You can also use that same shortcut to place new orders when you do not currently have an order in place for that company. You can only have one buy or one sell order open for any one company at a time, not more than one for the same company. As I type this @RogueTrader, you currently have only one open order, for $9,246.10 worth of AER (a buy order) at a maximum price of 15.5 cps ($0.155).
Whenever you change or cancel an order, the following evening when the orders are processed you will get a message saying that your order has "expired". Don't worry about that. It's just the way the system works. All edited orders result in a new order being placed while the old order is moved to the "expired" list. Cancelled orders also go into the "expired" list. It's just a minor bug, and doesn't affect the order process, it just results in these silly "expired" notifications that clearly serve no purpose. So when you edit an order, a new order is created and stays current while the old order expires, but the system won't tell you that until around 5pm to 7pm.
Maybe the Strawman giving the "thumbs up" is wearing gloves RT, it looks like he is wearing a jacket with buttoned up sleeves... Not normal scarecrow attire I have to agree...