What version of Premiere Elements and on what computer operating system?
Generalizing for now....
Open the program's Titler and create your watermark.
If you want a copyright symbol ©, hold down the Alt key and hit 0169 on the auxiliary
keyboard. Close out of the Titler, select the Timeline title file, and then lower the Opacity to about 50%.
Drag out the title file on the Timeline to span the duration of the Timeline content.
Have you tried that?
We will be looking forward to your results.