When you swipe on the trackpad from left to right, Windows 8.1 will automatically switch to your most recent apps. Is you want to display the App list instead, follow the below procedure:
- Open the Charms bar (Windows key + C) > Settings.
- Click on Change PC Settings > PC and devices.
- Go to the "Corners and edges" section.
- Turn off "When I swipe from them left edge, switch between my recent apps instead of showing a list of them".