To activate the formula calculations, check the Use formulas check box:
The sets having a formula will have the related caption of the column highlighted with a pale yellow background.
To have the formulas applied when editing the reference cost it is also necessary to select those sets whose costs must change after editing the cost in the reference set; this corresponds to the column highlighted with a green background. It is possible to check a set that has not a formula. After editing the reference set, its cost will be the same of the reference set, like in the case that the Use formulas box remains unchecked.
Notice that if the reference set has a formula, this will be ignored when editing its cost or those in the other columns; the formula will be applied only if another set is selected as reference set, before opening the Update cost screen.