How to open the control panel in Windows 8?
Control Panel 1: PC Settings
This is the start screen control panel. You can access it with a tap on Windows-i and the selection of Change PC settings on the Charms Bar (the sidebar that opens up when you run the shortcut).
PC Settings open up in full screen and the majority of changes that you can make here affect the start screen interface. From personalizing its look and feel to notification and searching settings. Some settings on the other hand are shared with the regular control panel, like the list of devices or homegroup settings.
Windows Update has also been integrated into this control panel.
Control Panel 2: Classic
Since there is no start menu displayed any more on the desktop, there need to be other ways to load the control panel. You can access it in the following ways:
While on the desktop, press Windows-i and select Control Panel from the Charms Bar (not PC Settings).
While on the desktop, press Windows-x and select Control Panel from the menu that opens on the screen.
While on the desktop, press Windows-r to open up a run box, and enter control panel.
While on the start screen, enter Control Panel and select it from the list of results.