Changing Page Scale and Drawing Scale

I want to change the scale of a existing drawing from ½" = '1 to ¼" =
1' 
When I change the current page drawing scale, the page scale changes but not 
the scale of the drawing.  In fact the drawing's scale is completed screwed 
up!



Is there a way to change the page scale and have the drawing also change 
scale at the same time?



Thanks