Your refrigerator can be raised or lowered by turning the adjustable leveling feet clockwise or anticlockwise (as shown by the arrow) if your refrigerator is not level or on an uneven floor.

Normally the front two feet can be adjusted.  But the two feet of the back can't be adjusted.

Almost all the feet can be adjusted by hands. When the refrigerator is put to the place you need, use you hand turn the feet.When the refrigerator is on even, it is ok. If the foot is too tight, you can use the flat screwdriver or other tool to adjust it.

If there are two  wheels in the front of the refrigerator. You shouldn't adjust the feet too high. It is best to let both of feet and wheels support the refrigerator.