The header logo and background can be changed via the Region admin tab.
Step 1: Open the Regions tab and navigate to Header
Step 2: Upload the header background and logo or select from the media library
Step 3: Save
Note: You will also need to add a Mobile optimized logo. Specs can be found by hovering over the i next to Mobile Logo.
You can change the header and logo so that it is unique for each channel via the edit current channel tab. The rest of the site design will stay the same for all channels. If you do not want a unique header and logo per channel then each channel will default to whatever header and logo you've put in your regions tab.
Step 1: Go to the channel you want to edit and navigate to edit current channel.
Step 2: Go to artwork>header.
Step 3: From here you can change the channel header and logo by selecting from your media gallery or by selecting an image from your computer.
Note: Specs can be found by hovering over the i next to Mobile Logo.