Develop Reference

How can I change the google firebase of my already linked android app, to another google firebase?

I had a google account say xyz#gmail.com which is not recoverable now. I was using that account's Google Firebase as the backend for my Android project say ABC App. What are the steps that need to be taken so that I can change the Google Firebase of ABC app to another Gmail account say qrs#gmail.com?
Thanks in advance!

Go to that project in Firebase in xyz#gmail.com in Users & Permission section add qrs#gmail.com user there as owner.You get email of invitation at qrs#gmail.com . Accept invitation. Now you can get all database configurations in qrs#gmail.com account.
No need to change any thing just alot qrs#gmail.com that database and you can get all stuff their.

I want to add user manually into Firebase and try to login into my app but getting error like "PLEASE VERIFY YOUR EMAIL TO LOGIN"

I have added the EMAIL VERIFICATION PART in my project.
So every user need to verify their email before login.
But I want to add some user manually in Firebase, and I did that also into my project and I successfully added that.
BUT main problems is that when I try to LOGIN using that email I am having error message like "Please verify your email...".
But as I told you earlier I added user manually in Firebase, so I didn't receive any verification email into that perticular account.
So is there any way to login using manually added users into my app?

Firebase Authentication doesn't check anywhere whether the user has verified their email address. So if your app shows a message to that effect, it's either your application code, or a library that you use, that is show the message.
Normally a user's email address is only changed to verified if they follow the flow outlined in sending a user a verification email. You can do this from your application in the same place where it now detects that the user is not verified.
Alternatively, you can mark the user as verified using the Admin SDK, after adding them in the console. For an example of how to do this, see update a user profile in the documentation. Keep in mind: the Admin SDKs can only be run in trusted environments, such as your development machine, a server you control, or Cloud Functions.

Firebase Authenticate Using Apple in Unity on Android without requiring login details each time

I have followed the following guide to get Sign in with Apple functioning on Android using Firebase: https://firebase.google.com/docs/auth/android/apple
When a user first logs into my app with Sign in with Apple they will be required to enter their login details and authorize my app. However, it seems that if the app is closed and reopened they will also be required to reenter those details each time.
Other Auth providers I have integrated have supported a silent authorization method, checking if the user has already authorized the app on this device or have given access to a refresh token which can be stored and used later. How can I access either of these through Firebase's implementation?

Firebase Auth allows an authorized session to persist on the Firebase side of things, without holding on to or reauthenticating with the other third party Auth providers. The key words to Google are "auth state persistence". Here's a link: https://firebase.google.com/docs/auth/unity/start

How do I get Specific user information through google, Facebook and twitter sign up?

for my app for android and iOS, I using Firebase Authentication with Google, Facebook and Twitter Sign In.
While using the above method , I want to make sure that I get the users' information as per the following
Name
Email
Password
Date of Birth
Gender
Country
Kindly guide me what all information could be profiled in my app after using Firebase Auth for google , Facebook and twitter sign in

Firebase only exposes the user's display name, and email address, and even then only if those have been set in the profile of the user on the provider they sign in with. Their password is only ever exposed to Firebase if they use email+password to sign in, and even then it is not stored in plaintext in Firebase.
For date of birth, gender and country (and some of the other properties too), you will have to request them in your application code and store them somewhere. Typically developers use the Firebase Realtime Database or Cloud Firestore for this.
For more on this, see:
Firebase: setting additional user properties
Add Extra Details on Firebase User Table
Adding Custom Attributes to Firebase Auth
Firebase - Adding additional user data to separate DB
Add extra User Information with firebase
How to add additional information to firebase.auth()

Firebase Account Linking (Email/Password, Facebook and Google)

I'm trying to use the linkWithCredential function from Firebase Auth, but I'm not sure whether I'm using it and understand it correctly.
We have a login page with 3 buttons in our app (Login with Email, Login with Facebook and Login with Google). When user login with any one of the providers everything works great (With every provider with its sign-in method).
But when user wants to login again in our app with a different provider we use the Firebase.auth.logout function and properly logging him out from Firebase.
It appears that we must need that the user will still be logged-in in order to link his account with a different provider.
Since user is not logged-in anymore I cannot use the Firebase.currentUser since it is null.
Do I need to get the current user provider by email, sign-in silently and then with that credential link it to the new provider? Also, it isn't clear whether we need to allow multiple account with the same email address enabled on Firebase console.
Is it possible to do that (linkWithCredential) without that option enabled?
Any help with examples on Android or iOS will be really helpful.