Each of the above sites and many other sites have general searches that are supposed to search everything, everywhere for results to your query. That does not seem to be what happens. What seems to happen is a search across the most used databases. Many times the results can yield hundreds of results and none of them may be what you are searching for. So …
On the first page of these sites is a menu option for “catalog, card catalog, or databases”. This is where the gold is found. Instead of just searching everywhere, search somewhere. Go to the catalog first and select a specific database and focus your search on one specific topic, event, era, person, or family. Don’t forget to read the “about this database” before you spend time filling in information on the search form. You may be in the incorrect database. This is particularly true when a database is limited to specific years.
So remember don’t search for everything: search for something.