All the pictures do appear darker then the real images (imported, in library or in development), compare to the result of the picture treated.
Where or how can I adjust the application so I have the real result. The first image shows how the image appear in opening it on my desktop. similar result if opened with my phone, so the problem is really how come all images opened in Lightroom are darker then normal. It makes it very difficult to work and adjust the photograph.
Lightroom is color managed, and will display correct colors as long as the monitor profile is sound and correct.
Most other applications are not color managed, and will not display correct colors. But Picasa does have an option to use color management, did you turn that on?
Another possibility is that a Windows update has installed a defective monitor profile.
Try setting the monitor profile to sRGB - if that fixes the issue, you should ideally calibrate your monitor with a hardware calibrator, which will also create a new, correct monitor profile. What make and model is your monitor?
Go to Control Panel > Color management, and follow the directions below to set the monitor profile to sRGB.
Rather than taking pictures of your monitor, you should create screenshots - see https://www.take-a-screenshot.org/windows.html