Auto transmissions are fairly reliable and should last more like 200K, as long as they are properly maintained and not abused. Given that you bought the car with 77k on it, you have no way of knowing if your fluid change was the first it ever had, or if the idiot before you beat the car senseless. When you changed the fluid, was the old stuff dark and smelled burnt? Was the pan full of sludge/glitter and did the pan magnet look like a hedgehog? Any of that would be a sign of poor maintenance or abuse, and an indication that the trans might be worn out.
Transmissions do have calibrations that change shifts based on driving style, but you've owned the car long enough that the old calibrations should have "aged out" and been replaced by ones based on your style.
Poor shift quality can also be caused by worn or dirt-clogged shift solenoids. Individual solenoids can be replaced, or the entire solenoid pack can be replaced for reasonable money. This wouldn't be worth doing if there was a lot of sludge in the pan when you did the fluid change though.
Transmissions do have calibrations that change shifts based on driving style, but you've owned the car long enough that the old calibrations should have "aged out" and been replaced by ones based on your style.
Poor shift quality can also be caused by worn or dirt-clogged shift solenoids. Individual solenoids can be replaced, or the entire solenoid pack can be replaced for reasonable money. This wouldn't be worth doing if there was a lot of sludge in the pan when you did the fluid change though.
