There are 2 language settings in LeagueRepublic, one is the language that you see the admin system in, the other is the language that is used on your public website.
Date formats are driven by this language setting e.g. UK dd/mm/yyyy and US mm/dd/yyyy
To change your language settings for your view of the admin pages go to:
My Account > Settings
Half way down you'll see a dropdown list of languages to choose from, remember to enter your password at the top in order to make this change to your account.
To change the language of the public league website go to:
Setup > Settings > General Site Settings
Again you'll see a dropdown list of languages to choose from.
(You may need to close browser and reopen it to see the change in your public league website)