Are Overwatch settings installation related or account related?

The settings are installation specific. They are stored in C:\Users\[username]\Documents\Overwatch\Settings\Overwatch\ so your best bet would be to copy the files in that location from your friend's computer to the same location on yours.

Unfortunately, gameplay settings like sensitivity and keybindings are account specific and loaded from the Blizzard servers when you login. You cannot copy them from an account to another, you have to re-setup everything by hand.

Graphics settings are installation specific and are located in Documents/Overwatch/Settings/Overwatch.