This screen lets you select one of six different zoom levels for the Spectrum Display. You can also change the Spectrum zoom level from the main tuning screen with a two-fingered pinch gesture inside the Spectrum Display.

wide means that the Spectrum Display will show a wide enough portion of the frequency spectrum to encompass the fundamental and all the relevant partials.  It is not useful for tuning, but it can be used to assess the strength of different partials in a note, or confirm that the correct partial is being tuned.

+/- 260, +/-130, +/-50 cents show the selected range of frequencies centered around the target pitch (at the selected partial).  There are green vertical lines in the Spectrum Display at +/- 100 cents and +/- 10 cents, depending on the range selected.

+/- 260(130) cents w/Mid 20 cents expanded shows +/- 260 or +130 cents overall. However the middle 20 cents (+/- 10 cents from the target) is expanded to fill a larger portion of the screen.  This gives the advantage of a wide range (260 or 130 cents) together with the advantage of a high-resolution view of the area immediately around the target pitch.  Thus you can see pitches that are far off from the target, and you also can get better precision for pitches that are much closer to the target.