You have already scraped your Roms using a template and you want to change template. Most of the time, it is necessary to restart a complete scrape of your Roms by applying a new template.
ARRM allows you to modify your template without having to re-scrape your Roms on the net. To do this, your previous scrapes must have been carried out with the '4 images' option activated (available in the 'General options' configuration tab) or that you already have the media and that 'they appear in the database.
If your database or your gamelist.xml contains these media tags, you can then choose another template and click on the 'Compose Image' button. ARRM will go through each of your selected Roms in the database and apply the new template. (this is faster than a scrape on the net)
If the tags are not present in the gamelist, but the image files do exist in the image directory, 'Compose image' will be able to apply the template by searching locally (in the downloaded_images directory or the one defined in settings) missing images.