If you drive fast and ride brakes hard you will get squealing... Drum brakes get over polished when you ride them hard and will resonate. nothing you can do other then replace the drum with OEM, DO NOT BUY EBAY!! I cannot stress that enough, I went thru 3 cheap drums on ebay then just bought OEM and lasted 3 more years..
this is commonly known as Glazing..
Pads to make a difference..