If it says “not found” when you enter the address- then the bill is mailed to some other address… so you need to put the APN (w/out dashes) in the bill number section. That will produce the owner’s name (or trust name.)
Take that name and plug it into the grantee/grantor search on the county recorders website…
That will give you a list of things recorded against the owner.
If the owner doesn’t have a bunch of properties it’s pretty easy to figure things out… If they own multiple properties it can get pretty confusing… Especially if they were chronic re-fi-ers. If it’s too hard to figure out you need to get the actual docs – either at a county office or by ordering online. If they only own one property you’ll see the deed, trust deed(s) (loans), any tax liens, absentee judgements, NODs, NOTs, etc…