Question

why might you use erasable ink? so that your words cant be altered so that you can make changes

Explanation:

Erasable ink allows for corrections. If ink is erasable, one can make changes to what has been written. Ink that prevents alteration (non - erasable) would be used for official, unchangeable documents. Since the question is about the purpose of erasable ink, making changes is the relevant function.

Answer:

so that you can make changes