Hello @SandraR869 ,
My suggestion would be to build some basic layouts for your campaigns - either by creating new ones or copying and editing already made ones - and include your branding, the basic structure you're going for with each one, etc. Once you have some templates made, you can put them into a folder and just name the folder something like "Master Templates" or "Branded Templates."
From there, you can copy one of these "Branded Templates" or "Master Templates," when you're ready to build a new campaign to send. This will allow you to have easy access to a blank canvas each time, and maintain the integrity of the original setup with each new campaign creation.