To Send One or More Images Backward One Place in the List

In the Raster Manager dialog, select the name(s) of the required image(s), or use the Raster Selection tool to select the image(s) in the view(s) .
From the Display menu, choose Send Backward.
The selected image name(s) moves up the list by one position. Simultaneously, the view(s) in which the image(s) appears updates to show the new display order.