I just did a stty -F /dev/ttyUSB0 57600
and a stty -F /dev/ttyUSB0 -a
the result:
speed 57600 baud; rows 0; columns 0; line = 0;
Then I upload a sketch with a:
Serial.begin(9600);
did another stty -F /dev/ttyUSB0 -a
the result
speed 9600 baud; rows 0; columns 0; line = 0;
so i believe changing the baud rate is not going to help. Time to look at the other configuration options that you changed in your first post.