In order to turn on or off the training mode, you need to click on the "Set" option on the home screen, which is located under the heading "Fiscalization". Ignition is done by clicking (not dragging) on ​​the gray switch that will move to the right and turn blue. The blue parts of the checkout header and the main menu on the left will turn gray. So whenever you are in "gray" mode you know you are in training mode.

Turn off training mode by clicking (not dragging) the blue switch, which automatically turns gray. Then the header and the main menu on the left turn blue and training mode is turned off.