How to login using a different user?… Let go.
Shift right-click the “OPC Quick Client” icon.
Enter user appropriate user credential.
From here onward you can configure the OPC client. This is specifically for Kepware Quick OPC Client.
Click on File->Open or File->New (if you don’t have a previously saved file)
Once the connection is made, Kepware Quick OPC Client should show a green icon next to the connection; as shown below.