Can I just point out something that may help?
Your personal hotspot can operate in two different ways as far as I know:
1 it turns your phone into a wifi hotspot that other devices can connect to and then uses the cellular connection to the mobile network to provide internet connectivity to those devices
2 it allows direct connections (via cable) from a computer and uses the cellular connection to the mobile network to provide internet connectivity to the connected device
the "password" you enter into your hotspot settings is actually a wifi key. This should be entered into other devices that connect to your phone via wifi. If you change the password setting on your phone, you will have to change it on all the devices that connect via wifi.
When you connect a computer via a cable it is not connecting to your phone via wifi so the password setting is irrelevant. you don't need a password for a direct cable connection because you can see that there's a cable connected between your computer and your phone!
I would guess that, if your computer is connected to your phone by cable, it might also be connected to it by wifi - therefore you might see 2 connections through your personal hotspot.