Macro to Enter Text in Cell B based on Change in Cell A?

So what I have is a spreadsheet where I want to track changes when I update an assignment.

My Project and Milestone are set and changed at certain intervals that I want to keep separate from the Notes.

When I update/add or change an assignment, I want the Note section to automatically pull in a phrase indicated which project, milestone and assignment has changed.

I've racked my brain trying to figure thous out in the Macros and gotten nowhere fast.

Any help would be greatly appreciated.

Below is a rough example of what I'm attempting to create.

Project	Milestone
PROJ X	MILE X
Assignment	Notes
Location 1
Location 2
Location 3
Location 4
Location 5	PROJ X, MILE X - Changed to Location 5