well you see in layman's terms it's because overtime she grew as a Jedi
her first lightsabers were normal Padawan blue
The second were turning yellowish green and green
3rd were Anakin blue
and look in the comics for her 4th set
then maybe make a little bit of an effort and write an essay on that subject? 20 pages 12 size font should be enough. you are welcome to make more if needed.