Turn all the stove's knobs to the off position, and remove the burner grates and cooktop to reveal the inner workings of the stovetop.
Locate the air shutters for your burners. These are located near the front end of the oven and will be either barrel-shaped or triangular. The shutters will be connected to the burners by metal tubes, and there will be a shutter for each pilot light, depending on how many pilot lights your stove has. (For example if each burner has its own pilot, there will be four shutters. If there is one pilot for each of the two burners on either side of the stove, there will be two shutters. If all four burners run on one pilot, there will only be one shutter.) There will be an opening on each shutter for letting air through and a cover plate that can be adjusted to change the size of the opening.
Loosen slightly the screw on the cover plate for the shutter that is connected to the pilot light in question. Do not completely remove the screw -- simply give it half a turn for loosening.
Turn the plate to make the shutter opening larger if the flame needs to be heightened. Turn the plate to make the shutter opining smaller if the flame needs to be lowered. Turn the burner in question on high to check the adjustment. The flame should be blue and should not be hissing or ragged.
Tighten the cover plate screw to secure it in place.