Early in the season, to use Last Season's stats in a personnel tile, click the Hamburger menu, then Settings.
In the Settings menu, click "Bulk Edit Personnel Tiles" in the top left-hand corner. This will edit all personnel tiles that are in the report at once.
Navigate to the Games menu, uncheck the box that says "All Games", and check the box that says "Last Season", and click "Save".
You will now see Last Season's stats populating for your Personnel tiles.
You can also do this for any Team Stats tile or Boxscore, by click the Hamburger menu, Settings, navigating to the Games tab, and turning the Toggle Switch to "Last Season".