In the options screen click on password, when you get there choose Garfield on the left one, the monster guy on the middle one, and the mouse with cheese on the right. Press ENTER at the top of the screen you will see the word levels click on it and scroll down and choose which level you want  

Go to Options Screen, and enter the following under Passwords.

• Level 2 Garfield, Odie, Granny
• Level 3 Chicken, Jon, Bear
• Level 4 Monster, Arlene, Mouse
• Level 5 Odie, Bear, Arlene
• Level 6 Jon, Granny, Garfield
• Level 7 Mouse, Chicken, Monster