OK. What you need to do is this...
Find an application on your new pc registry ,that resides in software, win64node and export it (as lets say, demo.reg)
Open it in Notepad.
Open one of the Arma.reg files you exported from the old PC.
Look for and copy & paste the directory structure
You should have had two Bohemia folders to export, do it for both.
Notice how when you edit registry files the path has double// just copy as best as possible.
If you mess up just delete the registry folders and have a second go.
As long as you don't delete the registries on the original PC you shouldn't get into trouble.
Alternatively, post the text (of the registry.reg opened in Notepad) here and I'll edit it for you.
DO NOT include the Game Keys !!! if you do post it here !!
Just replace that bit with **** ok?
Addendum (I like using big words
I reckon you'll get it though. Either editing whilst in the registry, the correct path, or in Notepad. Further, when saving in Notepad, remember to add the extension .reg and Save As 'All File Types'