Firebase resetting the key - firebase

Question

I am using Firebase as follow:
Post--
-Kwc6asRRI1SUqrigYeD <- First input
-> Date: 1:00pm
-> ID: 1
-> Content: Hello!
-Kwc6fXQsN2xIQtHOofZ
-> Date: 2:00pm
-> ID: 2
-> Content: How are you?
-Kwc6fXQsN2xRO39LDPD <-Most recent one
-> Date: 3:00pm
-> ID: 3
-> Content: I am good.
These are "pushed" thus an unique key is generated which can be used to display them according to the "most recent to old" (or ID:3 to ID:1).
Now, when I need to update a data, let say ID:1 post's content from "Hello" to "My name is Steve", then it still maintains the unique key even though this is the most recent one.
Post--
-Kwc6asRRI1SUqrigYeD <-Most recent one
-> Date: 4:00pm
-> ID: 1
-> Content: My name is Steve
-Kwc6fXQsN2xIQtHOofZ
-> Date: 2:00pm
-> ID: 2
-> Content: How are you?
-Kwc6fXQsN2xRO39LDPD
-> Date: 3:00pm
-> ID: 3
-> Content: I am good.
I guess I can delete the post and set a new one, but that seems inefficient especially if I have more data on each child.
Is there a way to re-set the key so that it reflects the time change (like below)?
Post--
-Kwc6fXQsN2xIQtHOofZ
-> Date: 2:00pm
-> ID: 2
-> Content: How are you?
-Kwc6fXQsN2xRO39LDPD
-> Date: 3:00pm
-> ID: 3
-> Content: I am good.
-Kwc6asRRI1KDodkeixk <-Most recent one
-> Date: 4:00pm
-> ID: 1
-> Content: My name is Steve

Answer 1

There is no way to update the key of an existing node (see 1, 2, 3). If you want a new key, you'll have to generate a new node with the same content.
But in this case it seems much more likely that you want to keep your data structure as is and instead add a lastUpdated timestamp to each post:
Post--
-Kwc6asRRI1SUqrigYeD
-> Date: 1:00pm
-> lastUpdated: 1508215054096
-> ID: 1
-> Content: Hello!
-Kwc6fXQsN2xIQtHOofZ
-> Date: 2:00pm
-> lastUpdated: 1507610306270
-> ID: 2
-> Content: How are you?
-Kwc6fXQsN2xRO39LDPD
-> Date: 3:00pm
-> lastUpdated: 1508128668412
-> ID: 3
-> Content: I am good.
With this structure you can use a Firebase query to get the results in the order you want. In JavaScript this would look something like:
var ref = firebase.database().reference("Post");
ref.orderByChild("lastUpdated")
.once("value")
.then(function(snapshot) {
snapshot.forEach(function(post) {
console.log(snapshot.key+": "+snapshot.val().Content);
});
});