In the Amazon Fees area, you can set your estimated storage time.

Once in place, this setting will be taken into account within the Profitability tab of an item's Details screen.

To access this setting in Scoutify, tap the settings icon in the lower right corner and scroll to the Amazon Fees section.

To change the Est. Storage Time value, tap directly on the number next to months. It will become an editable field.

Enter the value of your estimated month(s) and it will save automatically.