Set Datestyle

Hallo,

i have postgres 7.1 in Radhat 6.5
the Datestype default is ISO format

where is change default  Datestyle to Postgres format ??

i used Set Datestyle to postgres in plsql


test#>select now()         now
------------------------2001-05-21 09:55:36+07

test#>set datestyle to postgres;
SET VARIABLE 

test#>select now();             now
-------------------------------Mon May 21 09:56:19 2001 JAVT

but when i reconnect to plsql the datestype ISO again

Help me plz

Nizomi