To edit existing hotkeys or to create new ones, go to the Hotkeys menu.

To edit an existing action expand the Main item, select the action from the list and set a new value.
You can also add a new action which creates a new order by pressing a special key combination. Click the Create custom action button. In the User action item, a new sub-item will be created called <Empty Order>. Select a new action and click Set Action. The Order Entry panel will appear.
Select the parameters to open a new order and press Buy or Sell. The order will not be created, but once you execute this action, it will be initiated. After that it is possible to set a hotkey for this action.