Thank you for the feedback.
The answers as follows
– Portable WinSCP completely stored at mounted disk (VeraCrypt) including sites/configurations/logs
– Configuration stored in .INI file (same dir where portable WinSCP)
– Name - WinSCP.ini
– Only previous Site Bookmarks lost. All other config at place.
Making the tests I found the reason !
582 version stores site bookmarks under IP only
583 version stores site bookmarks under IP AND PORT
I have edited WinSCP.ini by text editor adding port number - and previous bookmarks are at place !
So during an upgrade from 582 to 583 users must change it manually.