If you are new to R365 and want your prior year (PY) sales to show up alongside your current sales on the Flash Report, you will need to import your ‘Historical Sales’. These are different than your ‘Beginning Balances’ that you imported during initial setup. Click the following link for more information on ‘Historical Sales’
If you are an established R365 user, but are not seeing historical sales in your Flash Report, or are seeing Historical Sales from the wrong days, review your Fiscal Year Setup. Ensure that your Operational Calendar for both the current and prior year is using the same weekday (M/T/W/Th/F/Sat/Sun) as the first day of the year
For more information on adjusting the day or date comparison, view this training article.