Change display size by scrollwheel.

[cryptogram]

I have two computers, both with Windows 7. On one of them I can change the display size of a Word document by holding Ctrl and scrolling the mouse scrollwheel, and on the other I can't, although I used to be able to. How has this change happened and how do I reverse it?

[macropod]

The scrollwheel's functionality is set via your Mouse settings. See under 'Devices and Printers' on the Windows Start menu.

[cryptogram]

Thanks. However, I find that (a) there is nothing to enable me to change this in Devices and (b) the problem only applies to Word. Web pages and Excel are fine.