When enabled, one or more rows of preset buttons are shown on the bottom of the display. This can be used to rapidly jump back and forth between different locations. They can be assigned to objects such as AIS targets and Own-Ship; in these cases the view follows the object.
A preset saves both the location and the display scale. Pressing the preset also changes the display scale. You can save different presets for the same object at different display scales.
Long-press on a button to set a position and display scale. Pressing that button centers the display on that location and display scale.
If an AIS target, Own-Ship, Mariners Tool, or waypoint is selected when setting the preset, then that object is used for the preset. The button takes the name of that object and "follows" the object as it moves. The object is automatically selected when you press the button.
If a preset is not attached to an object, it has the name "Preset N", when N is the number 1, 2, 3, etc. If you want to name a location, you can do this by creating a View (double-tap / Add Tool / Add View), giving the view a name, selecting the view, and then creating a Preset for that view.
A preset is cleared by jumping to the preset and then long-pressing the button.