The Subscribers menu item encourages your audience to subscribe to your bot, similar to subscribing to an email list. Every time you send an update via your bot, it’s received by 100% of your bot’s subscribers.
The Subscribers menu item is also where subscribers can alter their notification settings.
How to customize Subscribers Menu Item?
If you wish to change wording or image of Subscribers Item go to Facebook Messenger, choose Main Menu and click on Customize button on the Subscribers item:
When you open the edit you will see all options to edit text and image of the item, like this: