For example, I have app ABC version 2.3, an update over the older version 2.2.
How can I go back to the previous version?
I am using a Nokia Lumia 520 with Windows Phone 8.1.10.
It is not supported to roll back an app to a previous version via the store at this time.
App developers can only ever have a single published version of an app, for any given version of the phone (so it is possible for 7.x to have an earlier version than 8.0 which in turn can be earlier than 8.1).