|"Can the password be stolen from the clipboard?"|
Lets say this, the contents of the clipboard are retained until such time as they are overwritten by copying something else, or until the computer is restarted.
If needed you can clear the clipboard without restarting by using the free program CCleaner. Alternatively just copy something new onto the clipboard.
There are clipboard managers around which will show you what is on there but, as always, keep and eye out for any unwanted goodies or malware:
Always pop back and let us know the outcome - thanks