Your Steam version is most likely already at the proper version. Look in the Steam install folder, "SteamApps / Common / Silent Hunter 5" folder, right-click on the "sh5.exe" file, left-click on "Properties" from that menu, then click on the "Details" tab. You should see a line "Product version 1,2,0,0". Hopefully, you did not install into a Program Files folder, but rather something of your own naming choice, outside of the Program Files folders?...
