Actually this is super easy to do, no need for other sites or any thing like that. However it is only super easy when you know how...So my favourite search engine is http://www.google.co.uk, here is how to do it;
1. Browse to the search landing page of the search provider of choice; in my case http://www.google.co.uk
2. Let the page load
3. Click on the three dots on the top right
4. Select 'settings' from the list that appears
5. Click on 'View Advanced Settings'
6. Click on the drop down for 'Search in the address bar with'
7. Select 'add new'
8. You now see your preferred search provider in the list.
9. Choose 'add a default'
10. Happy days
Please note that this doesn't work if you aren't on the landing page of your search provider. I've tried it with google.co.uk, and also with duckduckgo and both work just fine.
Confused by this need to visit google first. I just opened up Edge went straight to settings and changed. Google was already in the list.