dash lights on a 2002 kia rio RX-V

2002 kia rio RX-V. - I got a question my rear defrost button has no light since i bought it (used) so I don't know if there should be one or not. When I push the button the light comes on the dash. Other thing is My Rear wiper button the light is on the way out how hard is it to change and is there any screws