Change store theme and theme image sizes settings
From Side menu:
- Go to My store - Theme - Theme settings
- Choose store your want to edit and Push to edit theme settings
- Choose a theme in Choose theme dropdown field (List of all free themes with live preview - https://fesh.store/themes.php)
Also, you can load preinstalled modules from this them
Do not select option Load default theme modules if you have more than one store in the account. This option will remove all existing modules
Also, you can change theme image sizes settings, like product image sizes in catalog page, related product images, images on product page etc.