If you want to save multiple people in a list in the database, you’ll want to call push:

String userId = user.getCurrentUser().getUid();
DatabaseReference newRef = databaseReference.child("users").child(userId).child("savedPersons").push(); //  

newRef.child("name").setValue(nameTxt);
newRef.child("surname").setValue(surnameTxt);
newRef.child("gender").setValue(genderTxt);
newRef.child("ageTxt").setValue(ageTxt);

This will create a new child node under savedPersons each time you call push(). To learn more on this, see the Firebase documentation on appending data to a list.

Note that calling setValue for each property is wasteful, and may lead to unexpected behavior down the line. I recommend putting all values in a map, and then adding them all with one call to setValue:

Map<String, Object> values = new Map<>();
values.put("name", nameTxt);
values.put("surname", surnameTxt);
values.put("gender", genderTxt);
values.put("ageTxt", ageTxt);
newRef.setValue(values);

I am new to android studio and firebase. I am trying to save a list of people to firebase like this. Idea is that the logged in user should be able to save information about some people.

String userId = user.getCurrentUser().getUid();
databaseReference.child("users").child(userId).child("savedPersons").child("name").setValue(nameTxt);
databaseReference.child("users").child(userId).child("savedPersons").child("surname").setValue(surnameTxt);
databaseReference.child("users").child(userId).child("savedPersons").child("gender").setValue(genderTxt);
databaseReference.child("users").child(userId).child("savedPersons").child("ageTxt").setValue(ageTxt);

It does not surprise me that it deletes the previous saved person when i save another one but i don’t know how to save all of them. I have this in my firebase but i need multiple saved users. How do i do it ?
Firebase screenshot