Nope, don't rotate passwords. Just don't. Best case scenario, you're wasting your time; worst case, people will actually make their passwords less secure by rotating them, e.g. some people would happily change "password123" to "password1" and call it a day.
Just pick a looong password once, make sure you don't reuse it elsewhere, and you'll be fine.
This is as per the NIST latest guidelines.
Just use Google Docs then. Yes, it's Google. Yes, it will somewhat tie you into their ecosystem but Google Docs are free, get regular updates and are pretty good overall. I've been using Google Docs for many years now. I occasionally use Office365 for work and Google Docs is just as good, if not better.