Does anyone know of a way to do this?

In a users properties > under the general tab > for department, we put the grade number, such as all the 6th grade students get the number "6" in the department section.

- Users are organized by the graduating year, therefore each year, the department numbers must change. I tried selecting the whole group and putting in the new department number but all that does is adds it in with the current department number. i.e. 11;12 . . . . I somehow need to change the whole group from "11" to "12". Is there
any way without doing each one individually?