1. Open Firefox
2. Enter “about:config” in the URL and press Enter
3. This will invoke a warning message ” as shown below, Click on the “**I’ll be careful, I promise **” button to open the setting page.
4. Locate the Filter text box and enter** “browser.tabs.insertRelatedAfterCurrent”**
5. This will show the key and its value below (which will be enabled)
6. Double Click on the option to Disable it.
7. Restart Firefox