There are two shortcuts for applying branding across multiple events...
- Client Templates
- Device Specific Watermarks
Client Templates allow you save a standard set of branding which is applied at the Event level. When creating a new Event in the Console, you can nominate a "client" which will then apply that set of branding to the Event automatically. See here for more on Client Templates.
Device Specific Watermarks
If you are always using the same watermark no matter what event that you create, you could use the "Device Specific Watermark" option to set the watermark once on the device, and then for each Event, you would simply need to go to the Branding section and select "Yes" Allow Device Specific Watermarks.
This would mean that the watermark set on the Device Page would be applied to the images even though you didn't upload any watermarks to this event.
See here for more on Device Specific Watermarks