This feature is only available on Premium Plan
You need to add the "photolock-watermark" class to every images that you would like to have a watermark.
<img class="photolock-watermark" src="/someimage.jpg" alt="someimage" />
Do not forget to enable the "Watermark" feature in your Photolock dashboard.
Our support team can install watermark lock on your site at no cost. Use the chat widget at the bottom right of the screen to request installation.