Preferences -> Language Preference -> Select English from drop-down menu. 
Restart Program.

I assume you don't read Estonian, so ...
Preferences - 2nd option on the tool bar
Language Preference - bottom option on the Preference menu.

It might be easy to uninstall and re-install the program, making sure you pick
English as the desired language when it's offered as an option (I think that's
possible)

Good luck!