But when I did as you suggested, it still returns that same result. 

Or when you say 'save settings', do you mean something else? 

I use xfce desktop environment by the way.

xfce4-pulseaudio-plugin always starts as muted with volume in low setting whenever I restart the computer.  This has been like that for more than a year. 

I didn't pay much attention to this it's no big deal in running my machine.  However, if this is related to something more serious problem, I thought me and other people should know. 

Anyone has any idea, please let me know. 

Thanks.