Can you explain a bit about each one does and which settings you recommend? Thanks

Thanks for asking. These settings are under Expert settings on the result screen. Most of them only show with a measurement microphone (a UMIK), because a phone can't measure timing precisely enough. In short: keep the defaults unless one of the cases below is yours.

• Listening area — One seat (default) / Sofa (several seats). With One seat, the measurement at your seat counts most and the correction is tuned for it. With Sofa, every position counts the same: a slightly gentler correction, fair to everyone. Pick Sofa if two or three people listen together. It needs at least 3 measurements, one at your seat.
• Align the left / right arrival time (on). If one speaker is closer to your seat, its sound is delayed so both arrive together, and the image centres. It is applied only when the measurements agree on it.
• Align only the bass and mids (below about 1.5 kHz) (off). The treble keeps its own timing. Try it if the image sounds odd with full alignment.
• Extended-bass speakers / subwoofer (off). Tick it if your speakers or sub really reach below 30 Hz; otherwise the correction leaves the deepest bass alone.
• Cut below the speaker's lowest bass (on with a measurement microphone). A steep filter under what your speakers can play, so the amplifier doesn't spend power on bass they can't reproduce.
• Bass optimisation at your seat (off). It shifts the bass of one speaker in time so both add up better at your seat. It needs the arrival-time alignment and One seat. Some prefer it, some don't: compare by ear.
• Match left and right at your seat (stereo image) (off). It evens out level differences between the two speakers' direct sound (at most 2 dB each way), for a more centred image.

Our recommendation: One seat, alignment on, the cut below the lowest bass on, the rest off. Then try Bass optimisation and Match left and right one at a time, against "No correction" at the same level.

Wonderfully helpful. Thanks