title: How to send a push notification to a user that is in my database using FCM? android
body: <p>For example, I need to send a notification to a particular user. When the user sends me a trouble-message, I will push a notification which notifies him that the trouble will be fix soon.</p>
  
  <p>Now, I have already created a push notification but even when the user is logged out it can still receive a notification. And when I'm using a different account it can still receive the same notification for the other user.</p>
  
  <p>please help me create a push notification that will send to a specific-signed-in-user. Thank you. (Sorry I'm new here in android.) thank you very much again.</p>