Change menu label on mobile template

Hello,

I want to change the menu label in my live-wire template. I found this post https://wordpress.org/support/topic/change-menu-name-as-displayed-in-mobile-1 and try to reply but it doesn’t work.

1. download the child theme here http://themehybrid.com/themes/live-wire-child
2. unzipped on my site and activate
3. edit the file wp-content/theme/live-wire/languages/live-wire-en_EN.po with Poedit, save and refresh my site but nothing change

Can you help me please?
Thanks