Hi @Anshu kumar and thanks for the reply. I am using Enpass on one device only - Windows 8.1. Enpass is installed on the system drive and only the vault is located on an external usb stick.
I launch Enpass. It opens the vault from my usb stick automatically (I've changed the vault location in preferences).
I type in the master password.
The vault is opened, BUT
I have to go to preferences and reenable:
browser extension support,
the "minimise to system tray" option
(other preferences which I do not use are possibly also lost)