Sorry for the delay answering. I had a large holyday.
Thanks. I tried the color manipulation tool, and it solved the problem.
For resolution, I see that is the expected 10m. I wonder if more resolution can be extracted if the RGB bands do not belong to the exact same points. Maybe using some deconvolution.
As this thread shows, the satellite moves a lot between band recordings, so how they match the location for the pixels of each band? There must be some displacement between bands.
Since the computer monitor can only represent 256 different colors for each band, some transformation is necessarily made, but I don’t know which one. Maybe it already takes the square root, o a logarithm (but in which base?). I searched in the documentation, but found nothing.