If the clock is displaying an invalid time for your current location, the most
straightforward way to change it is to change the timezone.
You can change the timezone system-wide with sudo dpkg-reconfigure tzdata
run in the terminal. If you want to change the timezone for the current user only,
tzselect command should guide you further.
Similarly, if you want to change the keyboard layout, you can issue
sudo dpkg-reconfigure keyboard-configuration and follow the instructions.