Use a database

Best practice is to manage all of this information outside Altium using its database integration sub-system.

You can link symbols and footprints via a table rather than trying to manage this information inside of a symbol (which is the wrong layer of abstraction) or in a library of symbols (grouping becomes arbitrary and difficult to manage as the library size grows).

Doing it this way means that you never have to mess with internal attributes and double-entry of data.

My approach

I use CircuitHub for library management. It's free and it's trying to be a Wikipedia of parts.

It plugs into Altium (and other tools) and provides linked symbols and footprints via a local database that is sync'd from the web (so you can use it offline).

You can add/edit/manage parts on the website and it automatically (via Dropbox) syncs those changes to your computer where you can use them in Altium (or any other supported tool).

Here is how you setup CircuitHub to work in Altium.

Here are the basics of component management in CircuitHub.

Disclaimer

I helped create CircuitHub, because I got tired of dealing with these kinds of problems in library management.

Two solutions:

1. Search Path

Add your library path to the system search path. It will look there to find any missing libraries.

To do this, use the "Available Libraries" dialog and select the "Search Path" tab. Add your path to the list.

2. Install Libraries Globally

Install your libraries at the system level then all your libraries will be available in all of your projects.

To do this use the "Available Libraries" dialog, "Installed" tab (you'll have to switch as it is not the default tab when the dialog opens and it looks identical to the "Project" tab layout).

Click the "Install" button and shift-select all of your libraries.