What do you do if your league commissioner cheats and changes your lineup after he has LOST to you, so he can play for 1st place
My league commissioner lost to me 277 to 273 after Monday nights game was over. He cheated by changing my teams lineup and replacing Tee Higgins with Jerry Jeudy, creating a 13 point swing so play for the league championship. This should NOT be part of the Commissioner's Tools.
83rd
ranked

Yahoo doesn't interfere in any way when it comes to Private Leagues including issues with a Private League commissioner. Using League Chat or directly emailing the commissioner is the best way to address any problems.
For a Fantasy Sports experience without a commissioner try a Public League. Yahoo acts as commissioner in Public Leagues where Fair Play and Sportsmanship guidelines are enforced.