Why are currents along the eastern coast warm while those along the western coast are cold

Currents along the Eastern coast are warm while those along the Western coast are cold:

Because,

Warmer waters that flow from the equator towards the poles wash the Eastern coastsBut the colder waters that flow from the poles towards the equator wash the Western coasts.

Due to the impact of the Coriolis Effect on the currents generating in the oceans, the direction and the motion of the waters flowing from north to south and vice versa is determined.

It is because of this phenomenon, the waters from the equator flow northwards from the east and the waters from the poles flows southwards from the west.

Earths place in space 

Ansradar; im guessing here; good luck : )