Venus is not the North Star. The North Star is Polaris, and it is called the North Star because its location in the northern hemisphere remains constant throughout the year as other stars move around it.
The planet Venus sometimes goes by the nicknames the Morning Star and the Evening Star, deriving from ancient Greek assumptions that the object was not one, but two stars. They called the Morning Star Phosphoros and the Evening Star Hesperos. Polaris can be found in the constellation Ursa Minor, also known as the Little Bear and the Little Dipper, where it lies at the end of the handle.