What is it due to?
Due to the cache stored when changes are made in PrestaShop, they generally do not appear. The solution for the application is to delete/clean the cache.
Starting from PrestaShop version 1.6.x, they store cache using Smarty.
Where is it stored?
The information is stored in the following directories:
cache/smarty/compile
cache/smarty/cache
img/tmp
You can find the directories in the PrestaShop installation folder.
How to manually clean the cache
If you want to manually delete the PrestaShop cache, delete all the files in those folders except for index.php, then reload the website and check the changes made.
You can use FTP or the cPanel File Manager to delete the files.
From the administrative panel > Advanced > Parameters > Performance you can disable or delete the cache.