I need to input the daily manufactured product quantities in stock. If I use the the update quantity on hand button it does not account for the existing quantities already, It only adds the new quantity. How can I input the daily manufactured amounts without manually adding the already existing quantity plus the daily manufactured quantity?

For example,

Day 1: I have initial stock for product set at 10 units.

Day 2: Add 5 more units. Total =15 Units 

Day 3: Add 20 more units. Total = 35 Units.