I suppose you’re thinking:

• If I clear the quickconnect bar every time, what’s the problem with it saving the passwords? => Well, what if I forget to clear the quickconnect bar?
• The quickconnect bar doesn’t save the password if you don’t type it in the bar (source: comment by Denis “If you don’t enter a password in the “Quickconnect” bar, FileZilla will ask for the password when you connect. But in this case, the password won’t be saved [...]“), so just don’t type the password in the bar. => Well, what if I accidentally enter it anyway?

As you can see, the risks are low but they do exist: all is set up as if it was conceived just in the purpose of getting you to make a mistake (no confirmation when saving the password, need to clear manually on exit). But fortunately, the FileZilla crew provided us with a solution a while ago: the “Kiosk mode”. Introduced in version 3.1.2-rc1 (2008-08-24), it will prevent FileZilla from writing any passwords to the disk if set to 1. It was updated in version 3.2.3 (2009-03-21) with a new possible value of 2 which prevents FileZilla from writing to any settings files. To configure the Kiosk mode, add <Setting name="Kiosk mode">2</Setting> withing the Settings block in fzdefaults.xml (in FileZilla Portable, this file is located in App/filezilla).
Beware: setting the Kiosk mode to 1 or 2 will not clear existing passwords, it will just prevent FileZilla from saving new passwords. To remove already saved password you need to do this manually (just clear the quickconnect bar).

Sources:

• Ticket #4009: automatically clear private data on exit
• FileZilla 3 version history
• Drag and Drop not working in Kiosk mode
• FileZilla 3.1.2 on Lunarsoft