What affects the strength of gravity between two objects?

Mass and distance affects the strength of gravity between two objects. Now, let us say one of the masses doubles then, the force of the gravity between the objects doubles. So, if the mass increases the force of gravity increases. Remember, the force of gravity increases as the distance between those two objects decreases. Let us say you wanted to do the same thing, but instead decrease the force of gravity between those two objects, you would increase the distance between those objects. * Take note that force of gravity acts between all objects. Let's take the classic apple falling form a tree example. Once the stem of the apple breaks, the apple accelerate toward the Earth's center of gravity at a rate of 9.8 m/s^2 (meters per second to the exponent 2). I believe that the example states that the effect of gravity is observed between any two particles in the universe that has mass.