Upload images to display on product detail. Upload featured image as main image and gallery as thumbnail images
There’re several predefined thumbnail product’s images size, catalogue product’s images size and single product’s image size. Which you have to set in “Woocommerce > Settings > Product tab > Display ”
– If you upload images before and want to regenerate thumbnail you can use Regenerate thumbnail plugin to apply your settings with thumbnail.
– After install plugin you go to “Tools > Regenerate Thumbnails”