X in either an X-axis or Y-axis field in the Chart Options:

X-Axis series configuration

Y-Axis series configuration

Visualization data labels

Trendlines / moving average / regression lines

Each series / field offers configuration in addition to the axis configuration. In this area the data itself can be controlled (vs the axis or facet like color). To configure the or generally follow the corresponding settings.
X in either an X-axis or Y-axis field in the Chart Options:




