The Confluence-administrators can set the global watermark. Click "Manage apps" – "WATERMARK FOR CONFLUENCE" – "Global Watermark Settings" to enter the Global Watermark Settings page.
If "Watermark in all spaces follow with the global watermark settings" is enabled, the watermarks for all spaces are determined by global watermark settings; if it is disabled, the space administrators can customize space watermark separately. For more details, please refer to 2.3 Space watermark settings