Before you decide to use device specific watermarks, be aware that a guest is able to use the same Gallery Card to display images from multiple Events (as long as the events are all created under the same Member).
E.g. you can create one Event for the Photobooth (with it's own branding) and a different Event for the roaming photographer (with it's own branding).
If you want to have multiple devices at one event, with different watermarks for each device/photographer, but all the images being delivered to the same Event gallery you can use device specific watermarks
Setting a Device specific Watermark
Device specific watermarks can only be changed when the device is turned on and connected to the Console.
With your Walker turned on, open the ELEMENTICE™ Console and click on "Devices" tab on the top banner of the Console and select the relevant Walker.
You are now on the Device Page and can access the Device Settings section at the bottom of the Page. This time, select the Watermark section header beside highlighted Device section header.
From here you can upload your landscape watermark first, and then your portrait watermark. Remember to pay attention to the recommended size of the watermarks (listed next to the Watermark heading).
Next, you'll need to configure the Event to allow device watermarks to override the Event watermark.
Go the Event Page and select the Branding Tab. At the very bottom you will see the option to "allow Device watermarks". By setting this to "Yes" you'll allow the Device's watermark to take priority over the Event watermark.