Do the earth's magnetic poles reverse, and does that affect dating the age of the earth?

The earth's magnetic poles have never reversed; north is north and south is south. Talk of pole reversals is theory. The only measurable change is that the magnetic pole has drifted a little, a matter of centimeters. What we do know is that the magnetic field is deteriorating, and fairly fast. That field protects us from the sun's radiation; without it there would be no life on earth. Because we can measure the rate of deterioration over a few hundred years, we can extrapolate, and it shows the earth cannot be millions of years old, because that field would have decayed away long ago. That is a real problem for evolution.