To change the order of the widgets in a report, there are a couple approaches. First, you can open the widget editor and use the movement arrows. To open the widget editor, click in the upper left corner of the widget as shown here.
At the top of the widget editor, there are small arrow icons for moving the widget up/down by one space, or to move all the way to the top/bottom of the page.
The other approach is to simply drag a widget by grabbing its header area: