Audio volume too low to hear even on 100%

Just installed 42.1 on a used computer that was wiped clean and given to me. I have audio volume control set to 100%, but sound output is like it was set at 5 or 10%, on all applications - internet, VLC player, etc. Sound is there, but too low to ‘hear’.
Actually, it was installed by a friend who is not available to help me with every little problem. I have very little knowledge of OpenSUSE, so please try to phrase advice as though I might not understand the jargon.
But thanks for any advice at all.

Never mind. Problem solved.

How? It would be nice to know - in case someone else might need that info.