You will not have only a small current element. There is no magnetic field in the direction of the current element. P is due to current elements from two yellow line sections. Now we have a way to measure the magnetic field just due to one current element. The point P moves when you make the above changes.
P is shown at the top left corner.
Click at the DC current source to change its polarity. You can enter value for the current source into the text Field. The moving black points represent the electrons moving with average drift velocity. If you enter a larger value for the current , the electrons will move faster.