The heat absorbed/added to the material causes the material to change its form from?

It can, but each material has a different amount of heat it needs in order to change it’s form.

Explanation:

For example, If you heat water, it will go from the liquid stage to the gaseous stage. It will turn into vapour. So it is changing the form of said material.

This change is mainly due to the breakdown of molecules and chains which enable reactions to happen when heat is applied, since it changes those bonds between molecules.