The September 2017 monthly rollup for W7 (KB4038777), W8.1 (KB4038792) and W10 (KB4038782) which includes the Cumulative Internet Explorer Security update has changed the layout and behaviour of Internet Explore 11. This update has brought back the search box beside the URL bar. This update also automatically changes tabs to be on a new line under the url / navigation bar.
You need to unselect the option to have tabs on a new line.
First right click the blue bar at the top of the page above the URL bar.
you then see this screenshot
If you want to remove the Search Box, simply uncheck the “Show Tabs on a separate row”. That will remove the search box and place the tabs beside the URL box again.
I haven’t yet found a way to keep tabs on a separate row and remove the Search Box