Windows 8 automatically sets the number of rows of tiles on your Start Screen to fit your display and monitor size.
First and foremost, this tweak involves editing the registry so the usual warning applies – create a system restore point and/or back it up beforehand.
Open up your registry editor by typing regedit on the start screen and press Enter.
Navigate your way to this key:
You can of course edit this key with a different number should you wish to and if you want to switch back to the default value navigate back to the key and simply delete the Layout_MaximumRowCount value.