I have PSE 10.
In the organizer when you click on a picture if you have the properties window on right showing, you see the file name, caption if you have one and under that "Notes".
Is there any way I can add a note at once to several pictures.
I can cut and paste one note to the next picture and then to the next but, I many pictures with the same note.
You have found the quickest method - cut & paste.
It's not possible to synch metadata in Elements except for tagging with keywords.