If you notice that your Mevo shot is editing on its own, it's likely that auto-pilot has been turned on.
To turn off auto-pilot, tap the More Options icon in the lower right corner.
Tap the Camera Assistant icon.
Tap Auto-Pilot. You should notice the white box that surrounds it go dark. This turns auto-pilot off.
Now edits will only occur when you tap, pinch, or drag your fingers on the app.