Depending on the screen resolution, Windows 8 determines how many rows of tiles will be displayed on the Start screen. In case of displays with low resolutions, you get three rows, while higher resolutions can accommodate five or more rows. You can reduce these values or increase them if you want to. For this purpose, you will need to edit the Windows registry through the Registry editor. Change to the Desktop view and press [Win]+[R]. Then enter ‘regedit’, press the [Enter] key and confirm that you're an Administrator check with ‘Yes’. Navigate to the key ‘HKEY_CURRENT_USER\ Software\Microsoft\Windows\Current version\ImmersiveShell\Grid’. Here, search for the DWORD value ‘Layout_ MaximumRowCount’. If you can't find it, create it with the command ‘Edit | New | DWORD value’. Open the value by double clicking it. Then enter the desired maximum set number as the decimal value (for example, 6) and confirm this with ‘OK’. In order for the changes to reflect, close the registry editor and restart the computer.
NOTE: For screens with high-resolutions, you can set the value to a maximum of ‘6’ against the standard setting ‘5’. Windows will not support values over 6, but you can always reduce the number of rows down to the minimum value of ‘1’.