I have had that problem with username/password for the whole time I've been on an iPhone (2 1/2 years now - 4s and now 5s) until just recently with one of the updates. Now, when I enter a username/password on a site, I click "remember me" and a little window pops up asking me if I want my password to be saved... I click "yes" and all is now well. I was never aware that it was possible to have that info saved as it never was, on either phone, until this recent update.