It would appear from your Balance Sheet/Profit& Loss that you are just starting with Manager so the stock values to date are your starting balances for the items. …
If we study the third item down
Code 100 - Purchase Price = 4, Qty = 125 this alone = 500 - Then 125 by 500 = 62500.
It doesn’t look quite right to have a Purchase price of 4 and an Average cost of 500.
Can I suggest that you have entered the Items total stock value as the Average cost value
Whereas for the first item Code 1 - The purchase is 100 and the average price is 100 - more logical
Therefore “to make the value in hand equal to purchase price * quantity on hand” you need to change the Average Cost to = the Purchase Price in the opening stock panel - For code 100 the Value on hand should total 500 (4 x 125)