The margin for desktop and mobile don't adjust independently.
The template "Template: Salt Life" will not allow you to edit the overall template to be more mobile friendly. The Blank with Header and Blank without Header templates are both mobile friendly. I went in and created a copy of your first mailing there called "2017 WPA Mobile template" and put it into the Blank with Header template. Send a test and you should see it adjust.
For your other mailing, you will need to go in and adjust the text boxes so that they reflect more of a margin:
Click the gear in the yellow toolbar and use the slider to adjust the margin.