Can u Help me pleeeeeaaaseeee!!!

I am new in my sw company and i have a serious problem. My company has a written program and 10 different companies uses this application. They used it through their LAN Network so their sql server stands on their main server. I must write this application to work in a harmony with these different servers. So the problem starts here. I must write the sql connection string as a line of code and use it in 50 different forms in a single application. because if i used normal connection string in every form for 10 different companies i have to change 9*50=450 connection strings or laine of codes as their server ip/name,userid and passwords differs from each other... PLease can u help me for this sad situation. I would be very greatful if u can write me an example code that i can take the server ip/name,userid and password from a notepad or xml or anything else for different servers and use it in code in order to minimize the change of codes.... Pleaseeee...if u help me I would be very greatful and pray for u....