How can I change my Heroku website to a custom domain provided by Bluehost?

I am new to Bluehost as well as Heroku website.I have deployed my website to Heroku already.

This is my website:https://vietalk-project.herokuapp.com/

I have searched around but all the guides giving different answer and I also found an answer from Stackoverflow but it has been around 8 years so I really want an updated answer that I could implement towards this process.

Here is the steps that I follow:

1. I have added the domain to heroku settings. Image may be NSFW.
   Clik here to view.

2. I have changed the bluehost dns host record to point to the dns target provided by heroku.(I have also tried the dns host record to point to the actual website in this case is vietalk.org like in the picture Image may be NSFW.
   Clik here to view.and I also try heroku.app.com in this case is vietalk-project.herokuapp.com) But none of this works.

I found some answers that says using Heroku Command Line but I wonder where should I use it: in my terminal or the terminal in Heroku app if that exists.

So can anyone provide the actual step into customize the domain with Heroku please?I have contacted the Bluehost and they said using vietalk.org in dns host record and wait for the dns propagation but I waited and saw nothing.