If you have played in a match where a team submitted the score, and the opponents also confirmed that score, it's unfortunately not possible to adjust the score of that match afterwards.
Nettla uses a complex algorithm which kicks in 60 minutes after a score has been confirmed by the opponents, which automatically changes players levels based on several factors of the match score.
Adjusting a score later on creates a ripple-effect affecting other players in that match, as well as other matches they may have played or are about to play within the same time period, and that is why the late-adjustment is not possible.