There are two commands which you can choose to perform operates on any variables selected in the Variables area. These are both available in the Variables menu or from the popup menu of the variables list itself.
The standard action commands are available in the Variables menu. For more details about these commands, see Performing operations on selected objects.
Choose Variables > Set to set the values of any variables selected in the Variables area. A dialog prompts you to enter a new value to which the variables are set.