Doesn't work how? You cannot redefine the style, or the text doesn't change after you do?
If the latter, you probably also have a character style or local formatting override applied. If the former, and restricted to one file, see Remove minor corruption by exporting. If it happens in all files or all new files, see Replace Your Preferences
Unfortunately this did not work. I have now reinstalled InDesign but it still does not work. I can not with mouse highlight paragraph style in the menus, nor links in menus. Perhaps the fault lies in the handling of the computer mouse?
Make sure in Windows, Aero is turned off, or magnification in text size is set to normal.