Connection string in class C#

I make accounting app

Need to add class with multiple Connection string

Type

Public class

database
Database name BSS_2018, BSS_2019...etc
Database username a
Database password a

Database2017
Database2018
Database2019
etc..

This is good way, but have new year must add string in ALL FORMS in APP.
Need to create class with this data
Some help?

What I have tried:

Using before this way with label

string BSS_2018 = Properties.Settings.Default.BSS_2018CS;
string BSS_2019 = Properties.Settings.Default.BSS_2019CS;
string con;
InitializeComponent();
yearlabel.Text = getYear();
public void PullData()
{
if (yearlabel.Text == "BSS_2018")
{
con = BSS_2018;
}
else if (yearlabel.Text == "BSS_2019")
{
con = BSS_2019;
}
}