change ssis connection.

Hi,

i have SSIS proj whice now it connect to server A (whice is our test server)

now i want to modified our project that when we want it'll connect to server B (Our Prod server).

now i'm looking for something global that will switch the connection strings whenever i want.

what i find so far is to declare var for each package and give the var default value and to create script to change the value of the var.

is there a solution that will be for all the project and i don't have to change each package (i have alot of pckgs).

Thanks in advanced.

Configurations, as referenced in your other posts.