Please describe your model in more detail if you want a better answer. I want to see the geometry, mesh, loads, supports, and material  definition.

What do you mean by 2D?  Do you mean a 2D analysis such as Plane Stress or Plane Strain?  Or do you mean you have planar surface in 3D?  Show me a copy of the Geometry Details window to confirm.

A special case where you can change the displacement and the Young's modulus and have no change in stress is the following. A straight beam with an axial displacement of 1 mm. Double the displacement and halve the Young's modulus and you will get the same stress, assuming a linear solution.