OK, I get it now.
You should fix this issue in your previous accounting system by making journal entry so you reduce your expenses and increase balance of some custom asset account which you can create called
Inventory on hand.
Don’t worry, this journal entry won’t affect your BAS figures. You just want previous accounting system to give you accurate P&L and balance sheet reports.
Then closing balance of
Inventory on hand in your previous accounting system must equal to opening balance of
Inventory on hand in Manager.
In other words, you need to fix your previous accounting system. There is nothing to fix in Manager since you are doing it in Manager the right way from day 1.
If you are using
Sales invoices or
Purchase invoices tab, then cash-basis report might give you different figures from accrual-basis. Cash-basis recognizes invoices when they are paid while accrual-basis recognizes invoices when they are issued. This can have affect on costing method of inventory too, that’s why figures are likely to be different.