Change title of bookmark in Preview
Instead of using Bookmarks, you can use Notes as the replacement to use custom title for bookmarked pages. They serve the same function, with Notes having more versatile usage.


Show the Highlights &amp; Notes in sidebar by pressing Command+Option+4.
To create a note, you can choose Tools &gt; Annotate &gt; Notes or by pressing Command+Control+N.
Select everywhere on the screen and write down the title for your bookmarks (You can also pick the notes background color).


Here’s the screenshot how it looks like:



I’m not sure which Preview version support this,but it should be available after OS X Lion 10.7.