To crop/resize a page, activate the media box and drag the appropriate edge of the page inward or outward. Other display boxes can be resized similarly by activating them first and then dragging the edge of the drawn part of the page. The other display boxes can never become bigger than the media box. The width of the dragging edge is color coded so you can easily see which display box is being affected.
If you need to precise numerical cropping/shifting, clicking the [tool] button on the bezel which is drawn over the page in Crop and Shift mode, brings up a dialog where you can enter the settings. You can also use this dialog to affect the corresponding display boxes for multiple pages. Above you see the dialog box that shows for the Crop Box. The dialogs for the Bleed, Trim and Art boxes are similar. below you see the dialog shown for the media box.
The Crop and Shift dialog for the media box also allows optional content scaling to adjust the contents of the page to its new size.
Anamorphic Index is a factor of the horizontal and
vertical scaling proportions, thus providing a numerical reflection of
the amount by which the current size’s proportion deviates from the
original size’s proportion.