Thanks for the reply.
I'm sorry that my original post didn't help but, when I'm told that I've got it wrong, it helps to know, so that I can have another go.
I've just Googled this line:
deselect photoshop elements
I've not even bothered clicking on any links because the sample of text from each page, shown by Google, throws up loads of references to 'Deselect' being on either the drop-down Edit menu or the drop-down Select menu. (I suspect that it depends upon which edition of Elements you've got). Further, it shows that pressing Ctrl+D performs the appropriate keyboard shortcut.
Hoping that helps,
Chis