You may need to change the database connection for your Management or Personalization Servers, this can be done via the Server Configuration Portal.
Firstly, to end existing connections to the Servers and to ensure no users connect during the process, you can to stop the Application Pools for the Management/Personalization Server in IIS Manager.
Click on Management/Personalization Databases, then select Create New.
Enter the details of the database connection that you wish to add, and select Create.
Once the database connection has been added, go to Management/Personalization Servers, select the Server that you wish to update the database connection for, then select DEFAULT.
You should then see a drop down menu for Database Connection, select the new database connection here then select Update.