Like the button says, it adds the specified moves. So if the piece is already a King (like it is when you first load the page), it adds them to a King. If you want to add them to another piece, you should first define that piece through the 'Set moves' button.
Like the button says, it adds the specified moves. So if the piece is already a King (like it is when you first load the page), it adds them to a King. If you want to add them to another piece, you should first define that piece through the 'Set moves' button.