The Town Manager in the case of the Town and the Superintendent in the case of the school may at any time transfer an unencumbered appropriation, balance, or portion thereof between general classifications or expenditures within an office, department, or agency. The Selectboard or school trustees may, by resolution, transfer any unencumbered appropriation balance or portion thereof within their respected budgets. Notwithstanding the above, no unexpended balance in any appropriation not included in the Selectboard's or the school trustees' budget shall be transferred or used for any other purpose.