How to change the default language in Magento
You can edit the .htaccess file in your Magento home directory. It is usually hidden and you will need to set your FTP client to see hidden files first.
Once you add the below code and clear the cache of Magento, everything should work the way you want:
SetEnv MAGE_RUN_CODE "here put store_code from BO for french version" SetEnv MAGE_RUN_TYPE "store"
The second line should be left as it is.
However, depending on your Magento version, the code above might not work. Instead, you could try editing the index.php file with the following:
Where the “procycle_fr” should be replaced with your store_code.