The probability is this has a really negligible effect whether you do really utilize hyphens for isolating words and underscores for a solitary expression. Best practice is extraordinary while making new pages yet I would exhort against about-facing to old pages and changing the hyphens and underscores. Changing the URL implies executing a sidetrack, which will lose you more esteem than this change would pick up.
Streamlining page titles
Next down from the URL it’s an ideal opportunity to investigate the page title – likely the most manhandled and one of the longest serving center on-page SEO elements. Your page title is the component on the page where it is most vital to strike a harmony amongst decipherability and SEO.