Where can I find the FIFO preview?
After import and calculation, go to Transactions and open the FIFO or Matching view, depending on the menu label used in the app. You will see each sale together with the buys matched to it.
How should I use it?
For each sale, the system shows the date and symbol, the number of sold units, the revenue and the list of buys matched in FIFO order with dates, quantities and costs. The total cost of those buys becomes the acquisition cost. The difference between revenue and cost is the profit or loss for that sale.
If something does not match, for example a missing buy or a wrong date, verify the import and edit or remove the transaction if necessary. Any change triggers a recalculation.