
Isabelle M. answered 06/11/19
Patient and Versatile Apple and Video Production Trainer
In CS3, it seems the default is bottom left, but it doesn't really matter since you can choose where you want 0,0 to be.
Bring up the rulers, and look at their intersection in the upper left corner. You'll see a cross.
drag from there to wherever you want the origin to be in your document. Similar to dragging a selection box.
Good luck!