Hi Paarthiban,
for "All Demand Consumes Preceding forecast" a demand first tries to consume forecast of the same period and if all demand is consumed it will then reduce forecast of the older periods. Example: A sales order is in November, then it will first try to consume forecast in November, and then in October, then in September etc..
For "All Demand Consumes Adjacent forecast" it will try to consume in November, and then in October or December.
For "All Demand Consumes current forecast" it will try to consume only in November.
Best regards,
Stefan