Would anyone with an understanding be kind enough to summarize how to move an app with all its files and preferences to

[Black Landlord]

Good stuff, thanks!

So, let's say I'm in the process of moving stuff, and I take an application's support folder from an old library, but don't know which, and have to decide whether it goes in the main library or in my user's library. What logic do I use to decide?
What happens if I put a copy in both places?
Where is the preference stored for the app to know which to use?
Thx.