Sudden screen re-arrangement

My android phone has suddenly rearranged all the icons through all the screens.
A new little white circle with 9 little dots has appeared on the home screen, and when you tap it, it goes to a page with "Search for apps" at the top, Suggestions underneath (4 icons), then All. Down the right side edge there's the alphabet, A to Z.
I've been seeing "A1 Search" a lot recently. Could this be something to do with that?
My best guess is that I've somehow got stuck with A1 Search, and I can't get out.
Phone works ok, apps work ok.
Ed