Start with the kind of change
Check camera movement first
A loose mount, table vibration, opening door, or cable movement can affect most of the frame. Secure the camera and wait for the image to settle before changing a threshold. A moving camera can create monitoring gaps as well as unwanted alerts.
Use zones before broadening sensitivity
Make a Watch zone around the area that matters. Use Ignore zones for windows, trees, screens, fans, reflections, shadows, pets, or other recurring background movement. Zones do not identify what moved; they simply exclude or focus parts of the image.
Calibrate with representative conditions
Run the Motion Sensitivity Test while the scene has its usual light and movement. Treat its suggestion as a starting point, not an optimal setting. Repeat after changing lighting, camera position, or the monitored area.
Suspension is a different problem
When a browser tab is hidden, the device sleeps, or camera access ends, monitoring can pause or stop. That is a monitoring gap, not a false alarm. Keep the page open and the device awake while monitoring.