There are two different ways to define non-cumulative key figures:
Before you can define the non-cumulative value, an additional cumulative key figure containing the non-cumulative change must exist as an InfoObject.
There has to be two additional cumulative key figures as InfoObjects for non-cumulative values - one for inflows and one for outflows. The cumulative key figures have to have the same technical properties as the non-cumulative key figure, and the aggregation and exception aggregation have to be SUM.
You can evaluate separately the non-cumulative changes on their own, or also the inflow and outflow, according to the type of chosen non-cumulative key figure in addition to the non-cumulative.
For aggregation, see
Aggregational Behavior of Non-Cumulative Values