
String cannot be changed
You have opened the Serial Numbers — Setup window and chosen the Automatic Creation... button
In the Automatic Serial Numbers Creation window, you have chosen one of the browsing buttons. The Create String for Serial No. window has appeared
In the String column, you have entered string that consists of digits only, set the Type as Number, and chosen either Increase or Decrease in the Operation column
In the Type column, you have changed the value from Number to String
You can apply Increase or Decrease operations only on strings of type Number. To change the type of numeric string from Number to String:
Change the value in the Operation column to No Oper.
Change the value in the Type column from Number to String