Change is a process where someone change something. According to google, “make or become different”. It doesn’t really mean that it’ll be better.
Improve is a proccess where we take what we have and introduce a change to make it better, which can be measured by the key metrics.
Changing a bad proccess
I think it’s makes absolutely no sense. Any proccess that exists, must have been evolved from something, to the current state. Unless we really understand the process (I’m not thinking of simply calling the inventor “Stupid”, - which may mean “I don’t understand and I don’t care”), there is only a random chance on that the change will actually improves something.