Hi,
if you want to extend validity period for Cost centre - KS02 & for Cost element KA02 and select particular Cost centre & Cost element - go to edit in main menu - select Analysis Period - press F6 - and change valid period as per your requirement
but we can't change one controlling area to another controlling area ,
if you do not want use cost centre , cost element whatever already created - just go and Block/lock for posting
Thanking you
Regards
Mahesh