Hello, and welcome!
I haven't ran into that issue myself, but someone else here with that model has had that particular issue with sound. Read the thread where you posted and try some of the steps mentioned in it - of course, skipping all that Realtek stuff; it's an Intel sound card.
You have to edit the file as root for any changes to be saved. The guy never got back with us further, so we don't know whether or not the suggestions actually solved his problem...
73 DE N4RPS
Rob
