They control your access to not only parts of your computer but the greater internet as a whole.
One way to make sure this information is recorded is to write it all in a small book that is then kept in a safe place, or create a file on your computer, or both!
When details change, as they sometimes do, update the recorded information, then if you forget some critical login information the book or file can be consulted to help with memory recall.
Sometimes a computing professional may create a login and password for you, perhaps to access some online service or another. My suggestion is to login into that service and change the password soon afterwards, not forgetting to update your recorded information, so you know access is private.
The chances of that person using your information is low but better to be safe than sorry.
