Customer Terms
You first need to create your customer terms. Navigate to Side Menu > Admin > Document Settings > Customer Terms. Here you can create multiple customer terms by clicking on the "Add New" to right of screen and give them a "friendly" name.
After creating your terms. You can choose to show one, or multiple terms within your document. For example if you create a Client Contract, you can now click on the Cog Settings Icon, top left of the Client Contract and you will see the "friendly" names of them. Click on these names to show or hide what terms you wish. To make a one of these terms the default navigate to Side Menu > Admin > Document Settings > Print Layout Settings and turn on the relevant customer term that you would like to use as a default.