Most Salsa content is created through workflows which include an option to change the template for that particular page type.
After saving your page, click on the blue "Publishing Tools" button shown on the right, here:
The links for publishing tools will appear on the left side of the resulting window. Find the "Change" link:.
If there is not a "Change" link then your organization or chapter only has one chapter. You'll need to add another template to continue this process.
if the "Change" link appears, then click it.
If you do not have a "Publishing Tools" button, then look for the yellow box in the upper right corner of the page. Click on the "Change" link there.
In both cases, Salsa will display an array of templates.
Simply choose the template that you want to assign by clicking on the template thumbnail. Salsa will confirm your choice by putting a red box around the thumbnail. Save your choice by clicking the "Save" button at the bottom of the page.
Now your page has been assigned a new template, and all of your other pages will continue to use either the default template or templates that were assigned to those particular pages.