Why does firefox delete all my usernames and passwords each and every time it updates?
every time firefox updates, it deletes all usernames and passwords as well as all bookmarks.
Wšykne wótegrona (2)
see this answer:
Is there a new profile created?
You can check if you have an "Old Firefox Data" folder on the desktop in case the Refresh feature in Firefox has been used and a new profile has been created.