The main reason is that the globe of the earth is a big magnet. The N pole of this magnet is always near the south pole of the earth, and the S pole is near the north pole of the earth. The same compass is also a magnetic pole, which is also made of the properties of magnets. Therefore, according to the principle that like poles repel and opposite poles attract, it can be explained that the compass always points to the south rather than the northwest.
There is also a magnetic declination because the earth's sphere can be said to be the included angle between the magnetic meridian circle at any point on the earth's surface and the geographical meridian circle. This is what we call magnetic declination. Just because the principle of compass and magnetic compass is the simplest device to measure magnetic declination, the history of finding and measuring magnetic declination is also very early. So this function is also a very practical function. According to the regulations, the magnetic needle refers to the North Pole N, and the magnetic declination is positive to the east and negative to the west. So it can also be explained that the compass always points to the south instead of the west and north.
The compass is still a very practical thing, and its use is very simple. After the compass is placed horizontally, the pointer of the compass will swing back and forth, so that you can accurately see the north-south direction. It is still very useful to get lost in the wild.