CHANGE_LABEL(app_data->alt_val_label, " ?", NULL);
CHANGE_LABEL(app_data->speed_val_label, " ?", NULL);
CHANGE_LABEL(app_data->track_val_label, " ?", NULL);
CHANGE_LABEL(app_data->alt_val_label, " ?", NULL);
CHANGE_LABEL(app_data->speed_val_label, " ?", NULL);
CHANGE_LABEL(app_data->track_val_label, " ?", NULL);