thanks for your reply. The DPI setting I am referring to is for my screen which is located in the Control panel - Personalisation - Display - DPI settings. "Make it easier to see what's on your screen". And YES it does change what fits in printed Excel margins. I only found the problem out by accident when I changed monitors and needed to increase the appearance on screen because everything was too small. Immediately when I opened one of my excel worksheets I found that all the margins and pagebreaks had moved. Adjusting the "zoom" level in excel when viewing the worksheet has no affect. So as a test I changed the "Screen" DPI (in control panel) to the same % as they had been created in on the other monitor. And they all reverted back correctly with the margins and page breaks in the correct places. It doesn't matter what monitor I use the same thing happens.
This is a big problem for me because I have spent years gathering data and setting it out meticulously in these excel worksheets (not using a template) so that it fits precisely within pages. I need to be able to email the sheets and also save them to disc for others to view- but need them to be view and able to be printed as I had set them up. Now after finding this problem they are not going to be able to unless they have their computer setting exactly the same as mine. (The monitor is set to its default resolution which is the best view).