Click on the Switch button, or press the S key. Note that the list switches from the Clements World list, starting with Tinamous, to the ABA North America list, starting with Grebes, or vice versa. (The world list, of course, also contains the North America birds.) You can switch back and forth any time you wish.
If you have a checklist invoked, the Switch button rotates between World, N.A., and Checklist modes. In Checklist mode, only the birds in the currently invoked checklist are displayed on the screen.
Mode switching is most useful when entering sighting records. Obviously, it is more convenient to be in N.A. mode when entering N.A. records -- you deal with 900+ birds, not 9,900+ -- and even more convenient to deal with only the birds of the state you were birding in, or the nation if you have the nation checklist add-on. The mode you are in is displayed in the title bar at the top of the screen. The currently invoked checklist is displayed, the number of birds in that checklist and, if you have the nation checklist add-on, the number of endemics in an invoked nation checklist.
The screen mode you are in, World, N.A., or Checklist, determines only what you see on the Main Screen. It has no effect on Reports or Sighting Record listings. (There are a few functions you can't perform in N.A. or Checklist mode, and you will be so notified if necessary.) When you are in N.A. mode (or Checklist mode), the number of species you have seen in the ABA North America Area (or the checklist geography) is posted at the bottom of the screen, and those species are marked with '' (double quote) in the list. If you have seen a species anywhere else, it is marked with a ' (single quote). In World mode, you see only the single quotes and your world-wide life list count is posted at the bottom of the screen.
With an item in the Options menu, you can cause AviSys to always start in N.A. mode. Otherwise, it will start in World mode.