Word has a habit of altering setting for some reason that I have never fathomed. Click File then Page Setup then on the Margins page alter the settings as you want them then click Default at bottom left.
If you are using Win98SE and Word 2000 normal.dot can be found in C:\windows\application data\microsoft\templates just delete it and when you next start word again it will make a new one. You will probably have to go to File, Page Setup and reset the margins as the Americans seem to like 1 and a quarter inch left and right margins. Once you have reset them to what you want click on default and OK. Should be OK after that.