On the map screen, tap the GPX icon. Then tap the gear settings icon. Then, In the right column, toggle the “Hide Waypoints on Low Zoom” on and off. Try both settings to see which you prefer most.
Like Joao stated, when you zoom out, for POIs like Gas Stations, in which there are usually a ton of, the screen becomes filled with them to the point that you can’t see what you were wanting to see by zooming out in the first place.
For that reason, you might skip enabling Gas Station icons until you need to start looking for a gas station.
