We can right-click a string object and change the state (control, indicator, constant, array, element) by right-clicking. Unfortunately, the current behavior is (partially) inconsistent in the way the display format (normal, /-codes, pass, hex) is handled. Here are some results (list is incomplete), the symbol <> means in either direction.
Control<>indicator: The display format is retained
Array<>array constant: The display format is reset to "normal". *(Also see below)
Control|indicator<>constant: The display format is reset to "normal".
(*note that if I drop a string constant into an empty array container, the format and element size is retained. Converting to array using right-click should do the same!)
Whenever a conversion involves a diagram constant, the current display format is lost. I think it should be retained!