Disable Display of Letters on Password (iOS) When typing a password in any password field on my ipad, it displays each letter I type for a short time.  I'm on the train every day, and I always have people looking over my shoulder.. just can't help that.  How can I disable this?

On Android, you can disable this in settings, but on iOS I can't find this setting anywhere.
The reason why you can't find the setting anywhere, is because such setting doesn't exist in iOS. I am not familiar with the Jailbreaking "world" in a sense where I haven't installed software from Cydia and such, but you can certainly try to find an app that does that. 

Please notice I said: "try", because it might not even be possible. 

On the other hand, the only reason for that is to make sure you've pressed the right key… I never liked it either but oh well.