Define Page Editor question

I am trying to change Shipping & Returns page using Define Page Editor, and it has no effect on the text which was put there earlier. I don't remember how I added that text in the first place, I might have added that text directly to the tpl......php page in MyTemplate or may be other place..
But still, why Define Page Editor doesn't work? Shouldn't it add the text to the file which should override any other file whenever that file can be located?
Thanks.

Check that the location/file is writeable
There should be a message in the editor page prior to loading

do you mean this message:

Note: you should always edit the files located in your current template override directory, Example: /languages/english/html_includes/MyTemplateName
Be sure to make backups after changing your files.

Editing file:
/includes/languages/english/html_includes/MyTemplateName/define_shippinginfo.php
?
so, it seems it edits the right file, right?
But nothing changes when I go to my website.

Found the problem: I was talking about Shipping page which can be edited through Define Page Editor which is not shown in the website, because I removed its side box. Instead the ez-page is used for Shipping, with the same info. I've deleted info from the first page now, so it will be empty next time when I forget again and come to edit it.