1. From the toolbar, click Tools and select Options
2. From the left-hand menu, select audio settings. Make sure that the correct microphone is selected from the menu. When you speak into it you should see the bar below it filling with green line.
Next make sure the correct speakers are selected. Choose the appropriate ones from the Speakers menu and test them by clicking the triangular play button to the right of the menu.
3. If your video isn't working, select Video Settings from the left-hand menu, and make sure the correct camera is selected.
4. Make sure you click Save to apply your changes.