Thanks I had followed this guide.
I also looked at other suggestions but can't find the solution

it seems strange to me I try to ask a more specific question

when i connect my samsung 27 '1920x1080 full-hd monitor
whatever resolution I try to choose with morphos I don't go beyond 1440x960
this is normal ?
in practice it is not possible to choose 1920x1080 directly using the external monitor?

will the maximum resolution I can have always be 1440x960?

Thank you.