When adjust the blue potentiometer ,please use a multimeter to monitor the voltage
Rotating Clockwise can rise the voltage while rotating counterclockwise could lower the voltage .
When the module output voltage can not be adjusted ( the output voltage is always equal to the input voltage ) Please adjust the potentiometer counterclockwise 20 laps (20 turns) or more till it works.
The image is for illustration
DC-DC Booster step up module Converter Regulated Power Supply