This article applies to the 123-reg InstantSite package.
This article will explain how you can change the category image width on your Image Gallery.
Scroll down to the Create your website section and click on the InstantSite icon.
Click on the Login button next to the relevant InstantSite package.
Click on the Edit link.
Click on the Image Gallery in the Site map section
Click on the Settings tab.
Enter your new category image width in pixels and click on the Save Changes button.