buttons; press 5 and you get 4.

My Kenmore microwave buttons are being weird. I will go and make something and press 5 to be 5 minutes and 5 seems to be 4. I press 6 to see what happens and 6 gives a 5. 4 gives a 3, 3 gives a 2, 2 gives a 1, 1 gives a IC u P.... whatever that is..... so confusing. The over head light for the stove turns the vent on. The vent doesn't work. The turntable off and on button turns light for over the stove off and on. My buttons are pretty much backward I guess. How do I fix microwave buttons?