It this cannot be done in QBO, then you need to remove the "instructions" on how to do this when this topic is searched.  A set of step-by-step procedures to edit a W-2 is provided, but if you try to follow them in QBO, they reference access to information and tabs that do not exist!  This is why I spent the better part of three days trying to figure this out, following instructions that appear in your platform and then being told that this function is not possible.  WFT?!