The variable which we choose / control the values of, is usually plotted on the vertical axis.

By convention, the dependent variable is usually plotted on the vertical axis.

The axis on which we usually plot the dependent / independent variable is determined by convention. However, this convention may be overridden by other graphing conventions.

The dependent variable must always be plotted on the horizontal axis.

By convention, the dependent variable is usually plotted on the horizontal axis.

Historically, the vertical axis was sometimes known as the abscissa.