How to add a logo to photos after they've already been uploaded.
In your Photo Manager dashboard, click on the gallery you'd like to add your school logo to. In the right sidebar, click on Gallery Settings next to the gear icon at the bottom. In the left sidebar, click on Branding. On this page, you can upload your logo image, and choose whether to apply it to the bottom right corner, or as a banner across the bottom of the images.
Please note, processing time to add the newly uploaded logo to previously uploaded images will vary depending on how many images are in the gallery.