Update wordpress version

Hello everyone!
I have many installations of wordpress and in all of them except in one I have in the dashboard a button for updating in my own language. But in my first installation, I haven’t this button. I have only the update button of wordpress for english version (never the spanish version). In the other installations I have two buttons. One for the spanish update and another for the english version.
How Can I fix this for my first website making with wordpress?
Thanks!!
Oliveiro