HosTek.com has a web-video on this issue.
"Use ColdFusion Builder With Your HosTek Account Tutorial"
If the video is not available directly, I presume that tech support at HosTek would be happy to forward the link.
You will be able to see all FTP connections in the 'File browser' view. Select the connection that you want to edit, right click and select 'Properties'. The 'Edit connection' wizard should be shown, here you can update the existing connection.