4S-wi-fi will not retain password in memory have to input password each time unlock phone

I have done a "reset" and it didn't help. If I watch the wi-fi screen in "settings" .. I can see that I get the "working icon" every few seconds although it remains connected.  Also, I have lost all the other wi-fi location passwords and have to re-input each time I visit the location.

worked just fine until last week.  any thoughts?  thanks. charlie