How do I change backgrounds in my PDF using Acrobat X?

Question

I have been wholly unsuccesful in changing my PDF background of certain documents.  It works for some, but not other documents.  Is there an easy explanation for this?  Here is the link to the PDF document I'm having trouble with:  http://www.geoffhayden.com/assets/eus.pdf
I am unable to change its background to any other color.  Thoughts?
I am using Adobe Acrobat X (10.1.2) on a Mac. 
Geoff

Answer 1

Daniel makes a valid point but that's not really what you asked for so here is one way to achieve the result you want.
What was "probably" done was to use Acrobat's Edit Object Tool.  This feature relies on you to have a couple of different types of graphic editing tools like Photoshop and Illustrator.  In this case Adobe Illustrator will open if you have it installed and selected as the editing application in the Edit Object Tool's preference.
The steps would be:
1.  Go to the page where you want to change the background.
2.  Select the Edit Object Tool
3.  Control+click the page and select "Edit Page..." from the context menu.
4.  In Adobe Illustrator, select "Layers" from the "Expanded Panels" on the right hand side.
5.  In the Layers panel, expand Layer 1
6.  In the Layer 1 expand the top <Group>
7.  Go to the bottom two items in that <Group> and select both items (Shift+click) named <Path>
8.  Select the "Trashcan" icon at the bottom of the "Layers" panel.
9.  The result should look something like this:
10.  In Adobe Illustrator go to File>Save
11.  Close the file
12. It should show up like you expect now on that page.
13. Repeat as necessary.
14.  Done