disappearing environment variables

[mark poole <netmonkey_uk yahoo co uk>]

Hello,

I have just compiled and installed the latest gtk and dependants (linux) 
and everything seemed to work find.

I updated environment variables thus (i installed to /opt/gtk):

CPPFLAGS="-I/opt/gtk/include"
LDFLAGS="-L/opt/gtk/lib"
PKG_CONFIG_PATH="/opt/gtk/lib/pkgconfig"
export CPPFLAGS LDFLAGS PKG_CONFIG_PATH LD_LIBRARY_PATH="/opt/gtk/lib"

PATH="/opt/gtk/bin:$PATH"
export LD_LIBRARY_PATH PATH

and everything seemed fine and worked. However when I turned off the 
machine, all the variable changes were lost  so gtk was no longer linked 
in.
If I update the variables again everything works fine, but again a power 
down causes the changes to be lost

How can I keep the changes 'cos its a chuffin' pain to relink everytime 
I turn the machine on

cheers in advance

--mark