How can I get my search function within email to go back through all saved emails and not just the past year?

I never had this issue previously, but now everytime I search a name, email address or whatever, it only goes back a year at the most. I am really aggrivated about this and makes searching nearly impossible.|||Many are having the same problem with the search feature. Yahoo thought they had it fixed, but there are still problems. There is no suggested fix ideas from Yahoo. Hopefully they will get it all straightened out soon.