My inbox is only showing me emails back to April 21. How do I see all of the emails that Yahoo has stored for?

I am trying to clean out my inbox, but now it only shows me emails dating back to April 21. I want to see all of my emails that are in my inbox. How do I change my settings so that I see all of my emails.|||This has nothing to do with settings. Just click "Last" for the last page and if you still don't get them, then they must have been deleted either by you or Yahoo.