The best way to customise your itineraries is by editing your brand (Organisation > Customise > Brands).
When editing your brand you can change the company display name, colors and font. You can also add your logo and a hero image. You can create additional brands with different hero images and you can create brands for third-party agencies that sell your trips.
You can add your website and contact details to your itinerary footer (Profile > Footer setup).
You can also change the layout of each item/service within your itinerary on the Preview page (option icon (three dots) > change layout).