The Primary Settings Screen is where many setup and non-tuning functions are done.

At the top of the screen are three buttons having to do with tuning files:

Load tuning

Save tuning

New tuning

Below those buttons are three more buttons:

Select tuning intervals

Auto announce on/off

Auto note switching direction

Below those buttons are two buttons relating to Over-pull:

Start over-pull

Over-pull setup

Below those are five more buttons:

Sweep sound setup

Partials setup

Do internet calibration

About Montal Tuner (which gives version and contact information and the complete manual)

more (which opens a page for historical unequal temperaments)

Below those buttons are three switches on one line.  From left to right they are:

Enable silence for unison tuning

Auto tone generation when the detected pitch is not close to the target pitch

Enable tone generation of all the partials at once instead of only the partial that is used for tuning

To return to the main tuning screen, use the large Tuning button at the bottom of the screen, or use the two-fingered Zee-swipe escape gesture.