Craziness, but I wanted to say Thank you and I fixed it. The fix was the usual sort of infuriatingly simple computer issue. So I decided to give the connections to a new arcgis online server a go one more time. I put in the same address as above, and then before accepting I added an S after the http. It worked, and I was able then to go to settings in locator and sort it all out. Don't know if it sticks, but I have a solution.
Thank you for sticking with me on this.
Paula