In Preview, is there a way to change/edit the names of links in the Table of Contents of a pdf?
Preview does not support this.
You need more advanced PDF editing software, like Adobe Acrobat Pro or PDF Outliner.
Preview can't modify or add TOC, but I find an alternative way to do this is use bookmark.
Just navigate to the page and press CMD+D, or choose "Tools/Add Bookmark" menu item, the page number and some text from the begin of the page will show on the bookmark view.
I use this way to add link to the PDF file without TOC, and it works.