Hi Zeze,
We make the form of something different by "changing" it. A change can be tangible (e.g changing of an outfit) or intangible (e.g changing of someone's mindset or decision).
Example: Please "change" the Word document to a PDF format.
We "exchange" when we give up our ownership of something to someone; in return, that person will give up something else to us. Similar to "change", there can be an exchange of intangible assets too (e.g. You can exchange your views during the meeting.)
Example: Please "exchange" your ticket stub for a complimentary drink.
I hope this helps.