Too many people hide in the dark behind the laptop. You should stand away from the computer and in the light. Use a remote mouse so you can walk away from the computer. Arrange the lighting in the room so you are in the light while the screen is dark. To do this well, you might even need to unscrew some of the light bulbs.
Motion attracts people's eyes.
Gesture to the screen when you want audience members to look there. Use moving text to grab their attention. Stand still when you want them to focus on the screen. Then move when you want to capture their attention again. Murphy loves applying his law to technology.