TODO:
You have a list of objects, and you want to update all items with a particular value, based off of a particular condition.
SOLUTION:
string newAccountNumber ="12345";
string previousAccountNumber = "54321";
foreach (var account in dsAccountList.FindAll(a => a.AccountNumber == previousAccountNumber))
{
account.AccountNumber = newAccountNumber;
}
NOTES:
The example will update the account number for all accounts with AccountNumber = previousAccountNumber