i go to different sites for lab work and use filezila portable version on a usb, this morning used a brand new usb with fresh installation of portable version, was surprised that all my quick connect history was there when plugged into a public site PC. is there a way to erase that history on public PCs?
FileZilla Portable stores your Quick Connect history within FileZillaPortable\Data\settings\filezilla.xml and FileZillaPortable\Data\settings\recentservers.xml. Neither of these files are ever stored on the local PC when FileZillaPortable.exe is run on an external USB drive. If you accidentally run filezilla.exe on the other hand or use the zip version from FileZilla itself, it runs in local mode and will store everything locally.
You can double check this by running a fresh copy of FileZilla Portable on your PC now and running it and noting that Quick Connect is empty. Then connect to a few servers and note the Quick Connect history fill up. Close FileZilla then delete the FileZillaPortable\Data directory which will reset its settings to the defaults. Run FileZilla Portable again and you'll see everything is empty.
If there's something else going on the next time you try it, please post again. If some random public PCs are somehow interfering with Windows environment variables, for instance, it could break FileZilla's ability to set its data paths which could mess things up. I've never heard of this happening before offhand, though.
Sometimes, the impossible can become possible, if you're awesome!