There are ways to update your permalink, or URL, structure so your links moving forward will be in the new format. However, what this means is now all your current URLs will stop working. So what you can do is set up redirects. This tells Google that the link is now located somewhere else. Common redirects include 301, which is the most recommended one for SEO, and 302, which is a temporary redirect. In most cases, you will most likely need to use the 301redirect option.