I usually set my hotspot password to some word / phrase I can remember, in case I want to add a new device to my phone or iPad. The default passwords are fine and secure, but it means I need to look at the phone and my connecting device every time, vs knowing the password and typing it in after enabling the hotspot and putting my phone away. Just personal preference.

Take a look at this tip at OSXDaily on changing the password for your iPhone or iPad hot spot