Hello, I had the exact same problem.
I’m following the YouTube tuts and see there is a Geometry button under the icon with the box and light. The Box and light is the placement button, it does not correlate specifically to Geometry. After toggling through the different options I found that “BSP” has the same items underneath of it as Geometry, so I’m guessing it was renamed in a recent build of the engine. I believe I am running 4.5.1. 