Photoshop clipboard not working HELP!

I had this happen to me cause I filled in the W and H manually .  I had to select a different Preset and then select NEW FROM CLIPBOARD  not it works as it should 

Could you post the signature image (or a lores version of it). 

" I have the signature image I want selected using the (W) tool, then I go to Select > Inverse (as online instructions indicate to do so), then Edit > Copy, then I go to open a new document Ctrl N, but the image does not show up in my clipboard in the new document. "

I do not see paste step in your description. After creating new document you shoud paste what is in clipboard.

If you can not paste because there isn't any content then something is preventing you from using clipboard and that is not fault of Photoshop. You must find that app or problem and fix that issue. Also take a look at this thread https://community.adobe.com/t5/photoshop/cannot-import-clipboard-images/td-p/9975424?page=1

Another possible problem is that you are not coppying what you expect to be copied. Do you work with layered file? Which layers is selected in the Layers panel?

To create new document that matches the size of what you selected: after you copy your watermark:

1. File > New
2. Click the Recent tab on the top row
3. Click Clipboard in "Your Recent Items" list
4. OK
5. Edit > Paste

But on re-reading question, if the goal is to create a watermark to add to your husband's photos, then just save the competed watermark as a .psd and use File > Place Linked to add it to one of his photos. 

~Barb