X windows are too big for my screen

[bigbagisbigbag <bigbagisbigbag post club-internet fr>]

Hello All,

I 'm new on Linux.
I work with Linux RH 5.2.
I worked but that is not easy to configure
with KDE (version ditributed with RH 5.2)
because my 14 inches screen is too small
to see all datas on the window 
Ex: I can not press Save or OK button to
set my mail server on Edit-Preferences-Mail
server on Netscape Communicator.
I 'm working in 800*600, but my screen can
not accept 1024768
Where and how can I set smaller window and 
message
box sizes in a configuration file.

Every idea or advice is welcomme

                             Thanks.

                             Bigbag