My computer screen shows the letters of fonts and format very small, when I switch to internet. I have sex buttons on the upper strip, named FILE EDIT VIEW FAVOURITES TOOLS AND HELP and in VIEW there is one option FONT SIZE. In it, I clicked at LARGEST font size, but it did not made much differnce. Moreover, whenever I open new internet site, its size is again smallest (as shown), but even if I click at LARGEST, it deos not help much, just minor increase happens.

Kindly solve my problem. Thanks...

The problem is that the web designers of many web sites (this one included) specify the font size that they want displayed, and so the View>Text Size option doesn't do anything for those sites. What you can do instead is try the View > Zoom settings and see if that works better for you.

Some historical perspective about this - back in the old days when the web was young an underlying concept behind HTML was that the user should be able to control many aspects of how pages were to be displayed. Things like text fonts, text size, and page width were considered user selectable, and the web browser would automatically adjust the display of the web page per the user's settings. But as the internet became more commercialized web designers became more concerned about the layout of their pages and how they would appear, and so began to lock down these attributes. So now most web pages allow little control, if any, by the user.

What browser are you using?

My guess is she's using IE8, based on the description of the menu bar:

Ah, good catch, the "Favorites" should have given it away.

Here are some options depending on the version:
How to Change Font Size in Internet Explorer 9 or Older IE