A humidity slider changes the drawer's storage environment on models that provide one. It is not usually the control for the entire fridge temperature.
What the observation tells you
The correct position depends on the drawer design and what is being stored. A high-humidity setting is not automatically suitable for every mixture of produce. Using it as a cure for warm milk or frozen items elsewhere confuses two different functions and may leave the actual problem unchanged.
A useful next step
Read the drawer section of the model instructions and arrange the intended foods accordingly. Keep produce packaging and the drawer's vent paths consistent with that guidance. If the slider is broken or seized, do not force it or alter the openings.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.