I see no way to select language once the program is installed, you could change your computers default language to the one you want to use, normally anyone installing a program would chose the language at this time and not need to change it again unless they made a mistake.
. . . . MEP 2014 you change language by clicking File > Settings > Language, . . . .
AFAICS this is referenced in the manual however there is no such option on my MEP 2015 Premium. The same goes for all the previous versions 2014, 2013, MX back to MEP 17.
There is also a reference to changing the interface colour scheme however IIRC this was removed when MEP 15 was introduced back in 2009.