My nexus 4 is not storing new Wi-Fi passwords. Each time I want to connect to a previous connected Wi-Fi I have to re-enter the password. I found that in Settings > Backup & Restore everything ...
I have Xperia Mini Pro that run on Android 2.3.3 I don't normally turn off the auto-sync, but my wifi is rarely turned on. I don't use 3G either. The problem is, whenever I'm in a wifi zone, though ...