When I select a face, the reverse face is selected (PC)

This is a known issue with some OpenGL graphics drivers. We have built a workaround option into SketchUp:

1. In SketchUp, open the "Window" menu.
2. Click "Preferences."
3. Click "OpenGL."
4. In the "Acceleration" section, select the "Correct reversed picking driver bug" option.
5. Click "OK."