Audirvana Plus Upgrade Problem

I am running Audirvana Plus, version 1.3.5, on a MacBook Air. It runs fine. However, if I try to upgrade I get the following warning:

"Audirvana Plus can't update when it is running from a read only volume like a disk image or an optical drive. Move Audirvana Plus to your Application folder, relaunch it from the there and try again"

I don't understand; Audirvana Plus is already resident in the Application Folder. What am I doing wrong?
Are you sure you are launching the one in the Application Folder? Is it possible that you are launching the one in the install dmg instead? I know I had made that mistake before. You might want to double check.

Yes, I think you are correct. How do I rectify this problem (I am not very Mac literate)?

If the one in the install dmg is newer, you need to drag the one from the install
dmg to the Application folder. It will ask you if you want to replace the one
already there. Just click Replace. This is the way to install many simple apps on
Mac. After that, eject the install dmg and you are done. Going forward, you
should always double click the icon inside the Application folder to launch