To watermark an individual file:
Right-click on the file, or open the More Options (...) menu, and navigate to More Actions > Watermarking.
Check Enable watermarking for this file.
Click Save.
To watermark all files in a folder:
Right-click on the folder, or open the More Options (...) menu, and click Settings
Scroll down to the section titled Watermarking.
Check Enable watermarking for this folder.
Click Save Changes.
Note If watermarks do not appear on watermarked file images in Grid View, try clearing your cache.