I am currently working on a multilingual project which uses around 12 different languages as part of Global presence. We thought it will be great if we can set a particular language as a default one for respective Content Authors ex. if we can set German as default language for the user who will take care of Content editing in German versions.
There were simple steps involved but I thought it will be helpful for others who follow my blog.
- Make sure that you have a content present in multiple languages.

2. Select the user (Content Author) in the User Manager.

3. Double click on the user.
4. Go to the Language Settings tab in the pop up.

5. Select the language you want to set for the user.

6. Click OK.
Now log out from the admin user and check logging in from the Content Author user s credentials.

There was a helpful blog which helped me to implement this requirement. Please refer it here.
Thank you.. Keep Learning.. Keep Sitecoring.. 🙂