I type in the Page summary box and click save but when i click edit again my changes to that box are gone?

That is correct. When you save, what is in the box should describe the changes you just made. If you do another edit, it is preseumably because you are editing it for another reason, so you will need to add another description.

That description is just an explanation when people review what changes have recently been made - it doesn't show up on the page itself.

Clear?

Thanks a lot :)