In some situation or some devices, Android keeps asking your WiFi network password. It can happen after rebooted the Android phone or tablet or disconnected and reconnected the network. This can happen due to the corrupted “DHCP” folder or “wpa_suppliciant.conf”.
We can mainly fix this Android forget WiFi Password issue two ways. They are respectively resetting the phone or table and the second method is delete “DHCP folder and modify the “wpa_suppliciant.conf” file. The second method need the root permission. If you don’t think it’s recommended the first method which is hard reset. If you need to root the device you can follow this tutorial (if that tutorial shows Android 5, it can apply nearly any Android version).
This tutorial I’m not going to show the factory resting method. It knows almost all of them. If you’re not you can follow my this step by step detail tutorial in here.