Fan control circuit only works at full power

I’m a total noob mashing parts together. Please dumb it down for me.

The battery is connected to a lipo handler then a motor controller then two fans, removing one fan doesn’t change the result.

I wanted to be able to control the fan speed with that motor controller but the fans only spin when the potentiometer is at 100%

3.7v 5000mAh battery 4010 5v fans

Thanks