A grinder setting is meaningful only alongside the grinder model and its counting method. CoffeeBox's comparison guide correctly identifies the central problem: the same click number on two different mechanisms does not establish the same grind. Click spacing, adjustment design and reference points differ. Descriptions such as medium or coarse are useful starting language, but they are not a precise cross-model calibration.
Find the starting procedure in the manufacturer's instructions for your exact grinder. Do not substitute a universal instruction to tighten the adjustment as far as possible. For example, 1Zpresso describes a resistance-based reference for several models and advises against operating the burrs near their contact point. The relevant manufacturer method takes precedence over a general comparison chart.
Once a suitable range is established, keep the coffee, dose, water and brewing method consistent while adjusting the setting in small steps. Record the grinder model, the reference used and the cup result. Sourness or bitterness can have several causes, so a grind change is an experiment rather than a diagnosis. A personal recipe log built this way is more dependable than copying a number without its equipment context.
The conversation
A good question can make a better brew.