Let's make it so you appear offline on Messenger even when you're actually online.
Messenger by default will let everyone of your connections know when you're online and using the app by the little green dot next to your name. However, if you want to use the app but appear offline even when you are actually online and actively using the app, this video is for you. I walk you through the option to toggle on or off the active status setting in the Facebook Messenger app.
There's no way to set this for one specific person, though, it's an all or nothing sort of thing and you won't be able to see who else is online if you turn your active status off. This trick works for both iPhone and Android but also on any PC or Mac computer.
I hope this video helped solve your problem. App still not working? If so, drop your question in a comment below!