Setting up multiple templates can be a big time-saver (How to create templates). If you want to switch between multiple templates, you can do so from any document using the "Edit design" option, available from the pricing table.

This button reveals a view that lets you alter the document's current design or select a completely different template.

Once you're done selecting your template, you can send finalize or send your document directly from this view, or click the "Back" button to continue working on the pricing table content.