When coloring, it is sometimes quicker to pick colors from the canvas. You can use the Quick Color Picker to do this.
Holding down when using the Brush tool activates a magnifying glass which you can see colors with. Releasing your finger selects that color.
If you feel that it is bothersome for the Quick Color Picker to be activated when holding down on the canvas, tap ①Settings.
Turning the Quick Color Picker off in the settings window means that it will not be activated when holding down on the canvas.
If you have the Quick Color Picker turned OFF you can still select the ①Color Picker tool from the Tool Selector window.