Changing default URL for Theme pages

If you go to the home page on my site and scroll down to the second section that has a yellow background and is labeled as follows:

Premium Service & Quality

In this section there are 6 boxes. Each box has a link to a page, however when I try and change the links to match the title then my page goes to a 404 page

For example
in the yellow section click on "SEO Consultants" it will take you to the following url:

If I change that URL to then update the link on the clickable symbol on the homepage I still end up on a 404 page when you click the link from either the homepage or the Services page.

I need to know how to be able to SEO optimize these links and when something is clicked it goes to the SEO optimixed URL instead of a URL like

how can I fix this please