How do I change the valve

Joanne, this could be caused by a water inlet valve malfunction. The valve has a diaphragm that is electronically controlled. It closes to shut the water off when not in use. Over time the valve can accumulate sediment and debris causing the valve not to seat properly. You can try and clean the valve with vinegar to remove any sediments. Clean it with running water after.You will need to remove the valve to do this. Should the cleaning not resolve the issue, you may have to replace the valve. For that you have to open the machine from the top:"

Remove the three screws holding the top panel in place.

Disconnect the hoses and electrical connections to the water inlet valve.

Remove the mounting screws holding the water inlet valve.

The part number for the valve is 906483 and a replacement valve is available at places like this. Attached image is from here.

I added the service manual to this page. Scroll all the way down to Service Documents and click on the blue link. Hope this helps, good luck.