A personal hotspot turns the iPhone into a Wi-Fi router that allows users to connect Wi-Fi devices to the Internet through the iPhone. This includes notebooks, tablets, portable game consoles and more. Be careful as tethering, as this is often called, can use data much faster than on the iPhone. If the computer cannot see the iPhone as a hotspot, users may be better off connecting by USB, but if that fails, try turning the laptop’s Wi-Fi on and off to find the iPhone hotspot.
Go to 'Settings' on your iPhone
Go to 'Personal Hotspot' and change the 'Wi-Fi password'. This password is needed to connect to your mobile hotspot.