On some ranges the upper element will come on for pre-heat. Then will shut off to let the bottom element maintain the set temperature.
If you are baking poorly you first should verify your oven bake temp with a separate oven thermometer. Compare this reading to your oven temp control. It is not unusual for temps to be OFF by 25 degrees vs the oven control setting. Some can be recalibrated, others you simply have to + or - your oven control.