Problem with Fuel Gauge

[Stigg ma]

Hi guys, I seem to have a problem with the fuel gauge of my 2010 Toyota Altis 1.6G AT. When i load gas at night, the gauge is at Full but then the next morning, I start the car and the gauge is now at the 3/4 mark. There is no fuel puddle under the car and no smell of gas inside or outside the car. My car is also parked in a secure place and the car runs smoothly naman. What could be the cause of this problem? Defective gauge or something else?
Thanks in advance!

sa users manual naka indicate dun kung kailan ang palitan ng fuel pump/filter assembly niyan, na abot mo na ba yong milage na yon?