Quick Snap is in the middle of the bottom bar. This feature allows you to quickly compare different signal path settings to determine the perfect tone for you.
To save a snapshot from a signal path, press and hold on the desired number of quick snaps (about 1 second) until it shows “Quick snap captured”, and you can click back and forth on the numbers to compare them. If you feel a particular quick snap is tonally the best fit for you, just click “Apply” on the top right to apply this signal path setting to this preset.