Answer:
1. Right click the taskbar and select "Show the Desktop".

2. Click once on a blank bit of desktop to bring the focus to the desktop and nothing else.

3. Hold down the Ctrl key on your keyboard, and scroll up on your mousewheel to make the icons bigger, or scroll down on your mousewheel to make the icons smaller.

4. Once you¡¯ve got the right setting - let go of the Ctrl key and rearrange your icons how you like them.