Why is my Yahoo screen smaller than my opening screen?

Answer 1

I assume that you mean that the text is narrower than the browser window.

Yahoo codes it's web pages in a way that the test area has a fixed width. Wider windows just display a background either side of the text, narrower windows get a scroll bar rather than the text reflowing.

I do not know why the programmers at Yahoo chose to do it this way. Possibly because it is easier to maintain the page format when you have mixtures of text and graphics.