Change watermark in a signature

Hello,

    I found this other forum post stating that you can change the watermark in a signature by going to C:\Documents and Settings\<user>\Application Data\Adobe\Acrobat\<version>\Security and dropping the image there. I tried it and it doesn't work. I have Adobe Acrobat Pro 9. The watermark is currently the adobe symbol.

Changing the watermark in a digital signature...

Any thoughts?