Hi Linda, 

if you need to apply a new template to an existing website you can proceed in this way: 

• Start a new Project by choosing the Template you like.
• On Step 2 > Template  choose Settings export/import, then select Export this Template settings to save the .iwtpl template file in a folder on your computer.
• Now open your project, the one you want to change template to
• On Step 2 > Template > Settings export/import, select the Import a new Template Settings option and import the .iwtpl file you previously exported. 

Thanks! Kind regards.