Mirror uses the same input for every client

Hello world! I used Mirror Networking quite a few times, but every time I get stuck at this problem. To test the game I build and run the game and connect to the editor playmode, everything works until I try to move a player: both players move at the same time with the same movement. I Tried to fix this putting the attribute [Client] from the Mirror namespace at every method but it didn't work. How can I solve this problem? Thanks in advice...