Only put a product in the compartment assigned to it in your model's instructions. A prewash option and a main wash are separate stages, and a misplaced dose may be used at the wrong time.
Understanding this situation
Drawer markings can look similar across machines while the drawer arrangement, liquid insert or automatic dosing system differs. A large compartment is not a reliable universal clue. Some programmes do not use prewash at all, so filling that section without selecting a compatible stage can leave product behind or produce a confusing result.
A useful next step
Identify the symbols from the manual and choose whether the laundry needs a prewash before measuring product. Avoid combining several detergents to compensate for an uncertain drawer arrangement. If product repeatedly remains in the correct compartment on a programme that should use it, note that precise combination for assessment rather than guessing that every drawer passage is blocked.
Manuals and supporting guidance
Model-specific instructions take priority. These references support the practical principles discussed here; they do not diagnose your appliance.