1. Open the Organizer and select the gallery you want to make changes to. If you open the Organizer from the gallery itself, it will be automatically selected.
2. Select either all the images in the gallery by clicking on SELECT ALL or click on the images you want to remove/change/re-apply the watermark to.
3. Click on the wrench icon > watermarks option.
4. You'll be redirected to the watermarking tool where you can select the action you want to take.
5. Don't forget to save the changes and be patient, as it may take a bit of time for the change to appear in the gallery. Also, refresh the gallery page in the browser.