Hello Texx -
The listing templates do not apply to stores, but individual listings and you can access them on the Lister page by selecting the blue button for Select Template that is below where you add your price when creating a listing. Most of our new templates have a new version of supersized images built in to them (see list in prior post) and we'll have the other new templates updated with the same functionality in the near future.
These changes will not affect your already active listings, but if you select one of the new templates on a listing you are preparing to post and use one of the abovementioned templates, the images in your description area will supersize when clicked.
If you run into difficulty with this, please let us know the details of what you encounter in a support case and we'll be happy to assist you.