I don't want them grouped in the taskbar. Let's say you have two different Excel files on your desktop and you double-click both of them. Normally it would open each file in its own instance of Excel, so as long as they aren't maximized you could resize the windows so that both workbooks were visible simultaneously side-by-side. Or in this case the user has multiple monitors and wants to maximize both windows, with one file on one monitor and the other file on the other monitor.
But suddenly, although the taskbar shows that two instances of Excel are open, both files appear in the same Excel window, in much the same way that two JPGs would be open in the same instance of Photoshop, with one tiled behind the other. So I am locked into a single instance of Excel. Normally each instance of Excel would have it's own toolbars (open, save, print, file, edit, view, etc.). But I'm just getting a single instance with one set of toolbars, but both workbooks (excel files) open -- one behind the other. I can switch between the two, but it's impossible to view them simultaneously on separate monitors. This isn't normal. It's only just started acting this way for no apparent reason.
Clicking the respective buttons on the taskbar that represent each file, by the way, just brings that file to the forground and sends the other file to the background, within that single instance of Excel.
Also, I already uninstalled and reinstalled and even ran a command that should have reset all the MS Office regestry settings to default, to no avail.
I hope this is a better explanation. Thanks for all your time (and hopefully your help

).