Use only the control arrangement and loading instructions intended for that appliance. A stronger setting may affect the fresh-food area as well as the small frozen compartment.
What the observation tells you
The fridge and ice box are not necessarily independently controlled. Trying to overcome an excessive fresh-food freezing load can therefore make other food too cold without delivering the required freezing capacity. The compartment's rated capability still applies.
A useful next step
Check the permitted fresh-food load and the control guidance. Use a suitable separate freezer when the task exceeds the ice box's design. Report any persistent inability to maintain its specified conditions rather than leaving the dial at an extreme.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.