Go to: System --> sprachen waehlen --> Pull down menu --> Select English
Then press "ALT+R" to initiate the change (You'll see in the bottom right hand corner of the window where you selected English from the pull down menu a word 'uberlaven' or something, the R is highlighted. Press ALT+R to use that command, which I think means next or confirm".
yast2 will do its ninja thing. When its done, close yast2.