Force can change a number of things about an object. These include:

• direction
• speed
• both speed and direction
• shape

Note that unbalanced forces can do any of these, since the net total of forces is not zero. In the case of balanced forces, nothing about the object will change.

When we apply a force to an object, we can change the direction of motion of an object. For example, a tennis player receives the ball from the other player, applies force on it (through his racquet) and returns it, thereby changing the ball's direction. We can also speed up an object by applying the force in the direction of motion. Imagine teaching a 4-year old how to ride a bicycle. We give the initial force to propel the bicycle in addition to the force the kid is applying on it, thereby speeding it up. We also stop the bicycle by applying force in the other direction, thereby reducing its speed, when needed. We can change both speed and direction at the same time by the proper use of force. Imagine slowing down your bicycle while taking a turn. The shape of an object can also be changed by applying force on it. An example is modeling clay, which can be given different shapes by the application of force on it.

Hope this helps. 

Give three forces that can make an object change shape.

I am not sure if this question is asking about force and physics or if this question is leaning more toward physical forces that change the shape of Earth's surface.  By definition, a force is either a push or a pull.  I could list out many different pushes or pulls to give three things that change shape, but I do not think that is what the question is asking.  I think the question is asking for three forces that can change the shape of Earth's features.  

1. Weathering and erosion—As surface features like rocks are weathered away through physical or chemical forces, the feature changes shape.  It becomes rounder, more sloped, or something else.  This is how canyons are made and how mountains are weathered down.  Materials are eroded, carried somewhere else, and then deposited in a new location which changes the shape of that general area as well.  
2. Compression forces at plate boundaries—This can cause breaks in the crust called faults.  Because the fault line is pressing together, reverse faults are created.  This kind of plate movement can also build mountains as the crust buckles upward.  This is what is happening at the plate boundary of India and Asia.  The Himalayas are still being pushed upward because of these forces. 
3. Magma movement—As magma makes it way to the surface of Earth, it pushes the ground up.  Even before a volcano erupts, scientists are able to track the shape changes in the mountain.  The mountain could get steeper, it could develop a bulge on one side, and so on.  After an explosive eruption, the mountain might not even exist anymore.  This is what happened with Krakatoa in the late 1800s.