looks like you have set the orders.clientsID to hold the ID of the user from the clients.clientID column
try using the following recordset:
SELECT clients.client, orders.borrower, orders.county, orders.image, orders.loannumber, clients.username
FROM clients
INNER JOIN orders
ON clients.clientID = orders.clientID
WHERE clients.username = colname
then create a new variable in the variables section as:
name: colname
type: text
default value: -1
runtime value: $_SESSION['MM_Username']