Lost passwords randomly

Suddenly one day I noticed that all my website passwords for the Android app disappeared. The passwords were strangengly odd themselves because some were very old, others were recent and many were incorrect when I would try to use them and it seemed to be very random and not how they were originally saved. Anyways, they all disappeared one day and I don't know why or how. Apparently I had got signed out of my account for Firefox which I didn't even realize that I was signed into an account through the browser. I don't use just one same browser for the web I tend to use a bunch of different browsers since they all are disappointing. I'm just wondering why they all got deleted and why couldn't I sync the ones from my desktop to my Android. Thanks for the help.