We all know the problem, we want to use a fancy way of displaying our links in wordpress. In my opinion the best way is to use the %category%/%postname%/ custom structure.
Let’s say your first category ever is called « home », it has the id « 1″ assigned. You can’t change this ID, it’s unique.
In the same situation, if you create a couple of posts and you couple all those posts to the categories « home » and another one -> only « home » will be displayed in your link (because wordpress chooses the lowest category id by default). The other category will continue to work, but it’s not fancy.
To solve this problem, there is a plugin you can use, called « scategory permalink » -> http://wordpress.org/extend/plugins/scategory-permalink/
To use is after installation is
1- Change the %category% in the custom structure to %scategory%
2- In a post, highlight the category you want to use in your link, and clic on the « primary » link that should appear
-> you’re done !
For more info, check the printscreens below