Updating Inventory Value for Previously input items

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I have used Square POS for Retail (free version) for the first 5 years my store has been opened.  I recently upgraded to the paid subscription.  One of the things I'd like to be able to see is the value of my current inventory.  I have been painstakingly entering unit cost on our existing inventory this last week, as well as entering unit cost as more inventory comes in.  On the dashboard, there is a "Total Inventory Value", but it seems to be only for new stock that has come in, not the previously existing stock.  How do I find the value for all my stock for which I have entered a unit cost?  Some of our stock might be around for a while, so I don't want to wait a year or two for it to be accurate.  Thanks!  If my efforts of data entry on existing stock are pointless, I'd like to know that before I put more hours into that!