2004 Chevrolet Impala Had Problems Starting Car Went Turn On Would Hear One

I had problems starting my car. When i went to turn it on I would hear one click and all the lights would dim. no start and the lights would come back on. I replaced the battery and the starter. Now the car starts, however the starter keeps turning over and if i leave the car on too long the starter burns out. I have had problems in the past with the starter but usually id have it replaced and it would work right away. I dont know why it keeps turning over.