If I enable auto upload option for photos or videos in the Koofr mobile app, is it enabled on all devices where I am logged into my Koofr account?

No. This is a per-device setting. If you enable the auto-backup option for photos and videos in your Koofr mobile app (Back up photos and videos on iOS or Upload new media files on Android), it will only automatically upload photos and videos from the device where this option is enabled. You can enable different options on different devices in your Koofr mobile app.