When you have any entry to reconcile, then the Reconcile Button will be visible.
On a clicking the reconcile button, you will redirect to the reconcile screen
You can find a statement button on a left side of the reconcile screen On a Mouse hover (mouseover).
On a click of that button, a statement form view will be open with the balance as well.
Check this demo video for reference
Please vote for the answer if it helps you.
So we have to create one statement for each transactions? how about the customer payment which has created before? even in your video link there are some amount in outstanding account from beginning and reconcile button has not available at the beginning and one more thing in bank journal there is no button for new transaction