If you are running Wifislax with a persistence changes file, you can use the command: sudo dpkg-reconfigure keyboard-configuration
By default, changes on a Live USB are not persistent. To make this permanent, you must create a persistent storage file when creating your Wifislax USB using Rufus or Unetbootin. Otherwise, you'll need to rerun this command each boot. How To Change Language In Wifislax
Some programs within Wifislax (like Firefox) have their own language settings: to download and apply an English language pack. Mozilla Support force-install If you are running Wifislax with a persistence
At the end of the existing line, add the following parameter: locale=en_US.UTF-8 add the following parameter: locale=en_US.UTF-8