If you right click the clock and then click "Properties" you should have a box pop up which is the properties of the task bar. There is a box that says "Icons" and a little explanation of what it is for. Click the "Hide inactive icons" box and the click the "Customise" button. Here you can select the icons you want and in the little drop down box select from "Hide when inactive", "Hide" or "Show". Hope that helps!