Originally Posted by EphICanIMite
Did you try seating the new head by pushing down in the center of the head lightly with the open palm of your hand? Set the drum on a pillow or other support so you wont damage the snares. I've found if you dont seat the heads in this way (applies to snare and tom heads), they will stretch out and detune as you play them. Just a suggestion. Also, if you can spare the cash... invest in a book called "drumset tuning theory" by Tony R. Adams. Was the best money I've ever spent related to drums. Saved me countless hours spent tuning and much aggrivation to boot.
I agree with EphIcanIMite. You need to seat the new head before you can truly tune it. I had the same problem with my ddrum
set. The tom heads always lowered after one song, so I decided to take them to my friend to see if he could figure out what was going on. He told me I should seat them, and maybe try to find some of those plastic rings that keep the lug from loosening. I use those and my drums seem to never untune themselves.