Yes, all of them. No, you say, that’s going to take too long. It won’t be immediate, but just google “identity theft” and you’ll find the time is well spent.
Password managers like 1Password or LastPass can aid in this process, as they’ll sync with your various devices using services like Dropbox or iCloud. Plus, they can generate strong passwords that you really only need to copy once, rather than try to learn or memorize dozens across multiple sites.
Only use one password across your logins? You’re asking for trouble. It doesn’t matter how careful YOU are, it’s how careless these web sites might be that matters. Password leaks are way more common than they should be.
Even “pro” sites like LinkedIn have experienced data theft, costing them $1 million just to investigate it.
The problem is not that your LinkedIn data might be misused, it’s that the thieves might guess the same password on your Paypal account or other web sites. This is bad. But memorizing a unique password for each web site is very hard to do, so that’s why these password managers are such favorites of IT professionals.
So do yourself a favor. Sure you can try that new diet starting January 2nd (Jan 1st requires ample snacks for football, we understand) – but if you really want to start the new year right, take time to modify all those passwords.