How to change the language in all user profiles

After some use of XenForo and attempt to upgrade to 1.0.1 in Russian we have all users profiles set to English, not to Russian as it was. Is there any way to set the language at once to the specific one?
 
Yes we still. And it works. But some magic occured - profiles become English. Is there any way to make it back Russian in bulk operation?
 
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