Kindly refer to MOS [ID 438598.1] "How To Change The Default Export Location For Discoverer Plus 10g (10.1.2)"
and "How to Change The Default Export Path For Discoverer Plus 10.1.2 [ID 365245.1]"
basically they explain the you can change the path in the pref.txt file and this is for all the discoverer users.
Also you can workaround it by following these steps:
1. Navigate to Control Panel >> Java >> Java tab >> Java Runtime environment settings >> View button
2. Set the run-time setting to be added in the "Runtime-Parameter" section
-Duser.home="c:\Documents and Settings\<should be change to real Windows user name>\Desktop"
I still can't get this to work. Are you sure you are on java version 6?
I have been to Oracle with the question and they have said:
"No its not possible (for java version 6) as this change has been disabled by Sun as being improper use of the user.home setting. More information can be found on the Sun website: