Use the Modify Value command to change the value of a
  simple variable.
 
  Expression:░░░░░░░░ ◄── Type a variable or expression
                                   THEN
  Value: ░░░░░░░░░░░░ ◄── Type the new value
 
  List:                             OR
  ░░░░░░░░░░░░░░░░░░░ ◄── Choose a watch expression from
  ░░░░░░░░░░░░░░░░░░░     this list and type a new value
  ░░░░░░░░░░░░░░░░░░░     in the Value text box
 
  To change the value of a structure or array, modify the
  individual fields or elements. You cannot change an
  entire array or structure at once.
 
  TIP: You can quickly view the value of an expression by
  typing it into the Expression field and pressing ALT+E.