Monitor problem, but if move track/mouse works well

Hello, the monitor of my MacBook Pro has flashing colors (especially on the bottom) and white points and other figures appearing and disappearing. I tried to update OS, reset and diagnostic as Apple suggest, changed logic board, but nothing happens, the problem is still there. The strange things are that if I move the mouse or trackpad the problem disappear. I also tried to connect via HDMI the Mac to TV (used two different TVs) and the problem is not only solved on TV but also on the monitor! Does someone knows what’s about, why if I connect to external monitor the problem solves on internal monitor too? Or if I use track or external mouse the problem solved too on retina monitor? Thanks