Hi,
When, you install / update HikaShop, Joomla will replace all its default files: translation files, view files, emails, controllers, etc.
So if you want to customize them you need to do so via overrides so that you don't loose them when you update:
- translations: If you want to change texts of HikaShop you should do so with translation overrides:
www.hikashop.com/download/languages.html#modify
In that case, the translation overrides are saved in the file language/overrides/xx-XX.override.ini and that file is not modified when you update HikaShop.
- emails: if you edit them via the menu System>Emails, then the modified email files are saved as separate files with the text modified. in them in the folder media/com_hikashop/mail so Joomla won't overwrite them, only the original files
- views: if you edit them via the menu Display>Views, then the modified view files are saved as separate files in your template's templates/YOUR_TEMPLATE/html/com_hikashop/ as per Joomla's MVC override system allows. The files there are also not touched by Joomla when you install/update HikaShop.
- images: if you modify directly the images, you'll loose them. You should instead upload your images elsewhere, and change the view file / email, etc using the default image to use instead yours.
- CSS: if you edit it via the interface in the CSS section of the Display tab of the HikaShop configuration, it will be saved as separate files in media/com_hikashop/css and you won't loose your changes during updates either.
So normally, if you follow our recommendations for overrides, you should not loose your modifications when updating HikaShop.