Button size in java

I want to control the size of the button, I use the setBounds method But there are no changes, and this is my code

       public class levels extends JFrame implements ActionListener{

 //Variables 
private static JLabel chooseLevel;
private static JButton easyPuzzle;
private static JButton mediumPuzzle;
private static JButton hardPuzzle;
 // End Of Variables 

this main cod

public static void main(String[]args){

levels level = new levels();
level.setBounds(400, 190, 450, 450);
level.setVisible(true); // frame is visible
level.setResizable(false); // not Resizable frame 
level.setTitle("Puzzle Number : New Game");  // Title Of the frame

Container for adding components

   Container cN = level.getContentPane(); //  Container to add components for farme 1
   GridLayout gN = new GridLayout(0,1,10,20); //object from GridLayout
   cN.setLayout(gN);

   levels.chooseLevel = new JLabel("              Choose a level :");
   levels.easyPuzzle = new JButton("Easy puzzle from ( 1 - to -15)");
   levels.mediumPuzzle = new JButton("Medium Puzzle from (1- to- 29)");
   levels.hardPuzzle = new JButton("Hard Puzzle from (1- to- 59)");

    //add components for frame

     cN.add(chooseLevel);
     cN.add(easyPuzzle);
     cN.add(mediumPuzzle);
     cN.add(hardPuzzle);
   }
   }
   }