if (user1.password.Equals(txtPassword.Text) || user1.Acct_Type.Equals(txtCheckIncu.Text))
{
LoggedIncubatorBankLogIn.Username = user1.username;
this.Hide();
IncubatorBank m1 = new IncubatorBank();
m1.ShowDialog();
}
You allow the login if either the password is correct
OR the Acct_Type is correct. You need to check that both are correct, and also use a securely hashed password:
if (user1.password.Equals(HASHVALUE) && user1.Acct_Type.Equals(txtCheckIncu.Text))
{
LoggedIncubatorBankLogIn.Username = user1.username;
this.Hide();
IncubatorBank m1 = new IncubatorBank();
m1.ShowDialog();
}