ForceDecks (and force plates in general) should always be zeroed before recording a test.
To zero your ForceDecks:
- Be sure that nothing is touching the force plates
- Click Zero Platforms
- An alert will appear for 2-3 seconds
- A new Test Recordings tab will appear on the top of your screen
Note: Try to minimise "noise" around the plates during this period i.e. jumping, dropping weights, vibrations near the plates etc.