If you are adding this data with GeoSetter - and your other posts suggest this - then you need to look at the preferences within that application.
Under File then Settings the first tab of options has a list of different file types. Select the file type you are using. There is a tick box for 'Save data in XMP sidecar files'. If this is ticked then there is another tick box below this for 'Always update Exif data (GPS and taken date) in image'. I think this is the option you need to have ticked.
Whatever you do please test this on some dummy images first until you are sure it does what you want.
but i can't do it with iview ,can i?
maybe expression media does it