I believe A:M configurations, including keyboard shortcuts are stored in the Master.MAC file in the A:M directory. Since each version of A:M has its own folder, each has its own MAC file.
In 64-bit A:M the file is called Master_64.MAC.
I don't know if simply renaming will make a 32-bit MAC work with 64-bit A:M so it may be necessary to keep MAC files for both 32-bit and 64-bit A:M if you use both.
you can update your MAC file by making your keyboard shortcut changes in the usual way, then saving a PRJ, then quitting A:M
You could keep versions of your MAC files in appropriately folders since the MAC file itself can only have that one name.
Copy the MAC file you want to use over the one currently in your A:M directory.