How to change current version of amarra to 4319??

Do a torrent search for Amarra with something like qbitorrent or vuze. Find whatever version you are looking for in the search results and download it.

You will need your activation code to load any new version. You will need a full Amarra license. If you forgot your code, email Amarra.

Steve N.
Empirical Audio

I should have mentioned that. You aren't doing anything wrong. A lot of people have a negative association with torrents. You've already paid for the software and have a valid reason to do this.

Another option may be to contact Amarra. They may have older versions of the software on one of their servers for download. People needing older versions of software is very common.