Since "Sunrise" is a fairly common brand name for budget and mid-range appliances (and often used as a model name by other companies), I cannot see the specific physical manual you are holding.
– Holding the “Sun” and “Breeze” buttons for 8 seconds doesn’t just reset the device; it recalibrates the ambient light sensor. The manual warns: “Do this only during direct daylight, or the fan will think sunset is at 2 PM.” sunrise fan manual