...when i select one row with opt.2 and press page down after that again i select next page one row with opt.2 and press page up privius page option cleared...
That's because you have to process the row with opt '2' before you can display the next page. You must either execute your change (revise) routine for that row or you need to store the information from that row so you can process it later.
If you choose to store it, you must do it it in some way that lets you store all rows that you find with opt 2 in them. That is, you'll store in an array or a temporary file or some other container.
The point is that you have a 'page-at-a-time' subfile. That is, the subfile only has a single page. Every time you display it, everything from the previous page is gone. You need to process those rows before you write the next page.
Try these links: