It seems that everything online requires an account these days. It can get confusing trying to juggle all of the different usernames and passwords you have to have for all of these accounts. Oh, and by the way, you're using a strong, complicated password too, aren't you? By strong password I mean a password that is, at least, ten characters long, has uppercase and lowercase letters, and numbers.
Most people use terrible passwords. Let's be honest, though, it's hard not to. I know you like to use passwords that you can remember, I just hope it isn't something like '123456'. I also really hope that you don't reuse passwords. That is a big no-no on the internet. There are so many password leaks each year. If your password and email address or username get leaked from one place, a malicious individual could use that same information to try to log in somewhere else, like your bank account! You don't want that. Thankfully there are smart and simple ways to keep things like that from happening to you.
How I Do Things
What if I told you that I can't remember any of my passwords? I can't ramble off any of them because they are too complicated for me to remember (except for maybe my home wifi password, but even that is complicated). I use a password manager to keep track of passwords for me. The password manager also generates complex passwords that are random and very hard to guess. If one of my passwords gets compromised on one site, I don't worry, because it isn't used anywhere else.
Get a Manager
KeePass - I've used a couple of different password managers in the past. The first one I used is called KeePass. It is free, and there are clients for it on Mac and PC, as well as iOS and Android. This one is a bit more clunky to use, but it works well. I highly recommend it. Here is a good video tutorial about KeePass on Windows.
1Password - The password manager I am using now is 1Password by Agilebites. There are versions of this for Mac, PC, iOS, and Android. This app is really clean and easy to use, but it is not free. They have a nice commercial about 1Password. It talks about their product as well as some of the reasons a password manager would be good for you. Here is a good video tutorial about 1Password on Mac.
There are many other password managers out there, but these are the two that I have the most experience with. They are both great apps and are both pretty easy to use. One nice feature for both is that they have web browser integration. What this means is that they can automatically fill in your username and password when you go to a website, so you aren't typing it in every time.
Where to put your password database?
I keep my password database on my Dropbox. If you aren't familiar with Dropbox, it is a place you can save your files that you can access from anywhere because your files are stored in the cloud. There are other services you can use that are similar to Dropbox, like Google Drive or OneDrive. Using one of these services allows you to access your files from your computer, phone, tablet, etc. This is essential for getting access to your password database.
It's much easier, and safer to keep your passwords in a secure password database, rather than in a text file, or Excel document or heaven forbid a notepad. Please tell me you don't have your password on a sticky note stuck to the bottom of your computer monitor?