How can I enable a chatbot to reply to all Facebook users' messages via Graph API on both Facebook and Instagram?

Question

I'm currently working on developing a chatbot intended to respond to messages from Facebook users. I've utilized the Graph API for this purpose; however, it seems that the bot only responds to the owner's messages and not to other accounts' messages. Is there a method or specific approach to configure the chatbot to reply to all users who interact with it on Facebook and Instagram? I'm particularly interested in enabling the bot to respond to messages initiated by various users. Any guidance or recommended practices to accomplish this would be greatly appreciated.