If you have set up your site to ask visitors for their location so you can serve them the closest listings in your directory, then their answer will usually be saved by the browser.
When that visitor returns to your site, they will not be asked again for their location, because their previous choice to be geo-located or not, was saved by the browser.
You can clear this saved settings:
- Firefox: https://www.mozilla.org/en-US/firefox/geolocation/ [6th question]
- Chrome: https://support.google.com/chrome/answer/142065?hl=en
- Internet Explorer: http://windows.microsoft.com/en-au/internet-explorer/manage-delete-browsing-history-internet-explorer#ie=ie-11