hi, if you have not triggered the action that lead to this notification email then please reset your firefox account password and your email password immediately!: https://support.mozilla.org/en-US/kb/im-having-problems-with-my-firefox-account#w_iaove-received-an-email-from-firefox-accounts-what-should-i-do

How do I change my firefox account password since you have to know the password to change the password. I can, however, change my email password immediately and I will. But can you clarifly how one can change your password when they do not have your password? And, how do I do it?

you can perform a password reset/change action for your firefox account through https://accounts.firefox.com/reset_password

if somebody has performed that procedure successfully it means they at least need to be in control of your mail account unfortunately in order to access the mail verification link to get the password changed (as you will see when you go through it yourself) - that's why you should change the email password as well!

I must have a spy, because there is no way my passwords could otherwise be compromised. Thank you Phillip for your help. I did, indeed, change all passwords.