Category links - how to shorten url to include section/category only?

Hello,

My client site was showing a top-level category link as
/<section title>/<category title>

This would link to the first article assigned within the associated category.

But when installing SEF registered version, these category links are now including the article title. Is there a way of easily switching off the article title for all menu items set up as menu alias links? (My menus then redirect to the first article in the section)

I need this since it looks much neater, since often the first article title is the same as the category title so there is repetition in the url:-

eg.
/mortgages/introduction/introduction
versus
/mortgages/introduction

The latter url was being produced before installing the registered version of the product
How can i switch it back to work this way?
I can't figure out the settings to use...

Many thanks in advance,
Natacha