When selected, text and dimensions show the value of the Symbolic Texts.
When not selected, the string which describes the notation is displayed. That is, the display of the value  of the symbolic annotation, rather than the string that describes it, is set by checking the Symbolic text expansion box.

In the case a symbolic text is unresolved,  that is, should the program still display the symbolic annotation, not being able to replace it with a proper value, you can decide whether to display it or to hide it by properly setting the Hide unresolved symbolic texts check box.

After selecting or deselecting this check box, click the Redraw Texts button to update the display.