Hi, Harry.
If you read very many messages here, you will see that this is a Frequently
Asked (and Answered) Question. The answers usually work, but not always.
Most posters are asking about Internet Explorer windows, although the
answers often apply to other windows as well.
The most straightforward way is to close all IE windows except one. Stretch
that one to fill the screen. Then close IE. When you reopen it, IE will
remember the size of the LAST window closed, which was your big one.
Trouble is, sometime in the future you may close IE's big window, only to
find a small pop-up behind it. Muttering to yourself, you close the pop-up
window - which IE remembers, since it is the last IE window closed. Next
time you start IE, it's the size of that pop-up window, so you have to do
the drag-n-close exercise again. :>(
Also, there are many ways to open an IE window: desktop icon, URL on a web
page; URL in an email message... Each of these has its own memory, it
seems, so you might need to "train" IE for each different method.
The way that it is "supposed" to work, but doesn't always, is to right-click
on the IE icon, click Properties, and then be sure the Run box says
Maximized, rather than Normal Window.
And remember, although they look nearly the same to us, Windows sees a lot
of difference between Full-Screen, Maximized and
Normal-stretched-to-fill-the-screen.
RC