You can check if you have had a security breach with an email account, by going to haveibeenpwned.com and inserting your email address. You may have had a security breach even though you have been using strong passwords. You can have accounts that have been compromised by the security failings of organisations that have stored your account details.
On haveibeenpwned.com there is a section where you can enter passwords to see if there have been any known breaches. If you use a password that someone else has previously used, and it has been breached, it is “burned” and no longer safe to use by anybody. haveibeenpwned.com/Passwords