Thanks. I pondered this and realized I could try using my Android tablet as a hot-spot and in this way get a different Internet Connection. And guess what, it worked after several tries and the LG Store updated the YouTube app. Then I reverted to my usual ISP connection and the updated YouTube is working fine, playng HD content for hours without a hicup - so I think this shows my Internet connection is OK. On my usual ISP the LG Store still refuses to install new apps, but at least I now have a work around. So, once again, thanks rsuprayogi