When you move button on a Question slide then please make sure you move button parent area don't move internal content of the button.
So, when we hover mouse on button then "Green background color" is used to depict OnFocus. Now if you move button content then hover area will be complete parent button area.
Please see attached screenshot to better understand.
So, in present question slide please move internal content of button in correct position or delete this Question slide and ad new question slide and move parent button area to change button position.
Let me know if this solve the problem.