Movement & Interaction
This difficulty arises from your choice of navigation. In third-person view, the space bar will not switch between aim and cursor modes. Please open the Options panel (default key O) and change your navigation to first-person view using the '1st person' button. Don't forget to press OK, or your settings changes won't be saved. Another tip is to use the mouse wheel to zoom in and out from first and third person views. View mouse help by pressing the default H key.