when we should use would, could, should??

hi friend! As my humble opinion using of should, would, could future form is "shall" past form is" should" as the same way "will" "would" "can" "could" Nd "should" is also used for "must", "compulsory",etc., nd "could" is also used for "asking in a polite manner" Eg:- could you mind turn on the light please.

I don't know

would, could, should is also used in "direct and indirect speeches"

For example we can use : he could write neatly ,he should complete his homework