good point made on this is not to use the same password for everything you use.
i tend to have 8 different passwords i use, with 4 that only get used for one thing such as email address, facebook, online banking, paypal and applestore.. rest are broken down into how safe i need something/regard it with one i use specifically for sites where money can be used and another for forums and the last for sites i feel are a risk..
when it comes to changing passwords you should never have to change your main passwords as they have never been used elsewhere, and the ones that could be at risk to things like this arnt linked to important stuff so its no biggie to change really.
thats just my philosophe on it im sure others may disagree