The way the pump sits in the tank causes the fuel level to rise when the nose of the car is higher than the rear of the car. The level went down to where it really is once the car was on level ground and moving.
You can't change when the fuel low light comes on, it comes on when it reaches around 3-3.5 gallons left in the tank.
You should never rely on the DIC for accurate numbers, do the math by hand and reset the anolog tumbler in the dash every fill up. When the low light comes on figure you have a short distance to go on the tank, then after a fill up or two, youcan gauge the distance you can go on a given tank.
