When you build a new site on 7.1 you choose a 7.1 "template" which is really just a layout, color palate design different from another 7.1 "template" . After its built if you want to change "templates", you tweak your site to look like a "template" you didn't choose. Unlike 7.0 where changing from one template to another in the same family is one thing but can be quite a challenge and a huge change in style and features from one template family to another. The second usually requires a new buildout.
Nice site, I am also an Avenue User, two sites. Its a great classic look, really good for photographers and artists, in my opinion.
https://www.dcmrblueridge.com/
https://www.myrandomviews.com/