Hello everyone !
I’ve already installed and developed website on Shopware 6. English language was used as default during installation. Customer wants to have german language as default for products. And there have been already a lot of content added, so there is no way to reinstall from the scratch (and choose german as default during installation).
Is it possible to change default language of products on already installed website ?
No, it is not.
You cannot change the default language after installation via the system. Only with changing several entries in the database, which can be risky.
You cannot have a special language only for products.
Thank you for the quick answer 
I did find a solution. System language is stored inside the code and not within the database. If you wish to change the language of the System, do the following:
- Select the Table Language within your DB
- Copy the ID for your System language
- Be sure to remove the prefix 0x from the ID.
- Look up your Code to find the ID you copied earlier
- You should be able locate the ID in the following files: common.js, Defaults.php, shopware.js and common.js
- I changed the ID to the one I wanted to use as default language within the Files above.
Be aware that it might not be safe to take this method and create an extra backup prior to.
This Solution was successful, I just required to change the Names of Product and so on to the default Language
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