Can't Set Default Date Format on Startup!!!!

I'm running oracle 7.2 on Windows NT with OS/2 clients. I can't seem to set the default date format. I've put   nls_date_format = 'mm/dd/yy'
in my parameter file but it seems to have no effect. The system still insists on dates as per 01-AUG-96 even though the result from a show parameters command is

  nls_date_format                     string  'mm/dd/yy'

If I do
  alter session set nls_date_format = 'mm/dd/yy'; after logging on, the date format is indeed changed for my session. How can I make this happen automatically for all users when the system starts up.

Any help would be greatly appreciated,

gene hubert Received on Mon Nov 18 1996 - 00:00:00 CET