Unity 2018.1b UI Buttons Issue

in unity 2018.1b, i am using 2 panels and in 2nd panel i have 4 buttons which are set at 4 corners of canvas. when i change my scenes and come back to current scene my buttons position changes automatically, even though the pivot of buttons are at their previous position. What should i do?

Attachments Process:

  1. made scene as described
  2. saved , took screenshot
  3. started another scene.
  4. came back to the scene with previous canvas.
  5. took screenshot again3391027--266596--after changing scene.PNG 3391027--266597--before changing scene.PNG 3391027--266596--after changing scene.PNG 3391027--266597--before changing scene.PNG 3391027--266597--before changing scene.PNG

Could it be this issue?
https://discussions.unity.com/t/690409