What is your definition of "local" and "global", because I think you're misunderstanding something.
If you move an object, you're moving it in the global space, so your local position won't change.
If you want to change the local position, you have to change the origin.
If you set the position in the global space to a specific value, it will always have that value.
If you want to move it by 250.f units, then you have to call move().