Typically you will see this in your drop down navigation if your site offers it. If not, this tutorial will not pertain to you. If so... let's move on!
1. Log in and go to your new Menu Manager.
2. Find the Menu Group you want to manage where your site link will be.
3. Click on the icon that looks like a menu group
4. The ONLY way to change a site link is to remove the existing one... but before you do that... let's create your new one first!
5. Near the top, click on "Add Link"
6. Pretty Straight forward, put in the new name for your site link and add the FULL URL
7. Once you have this in there... save it... refresh your page ("it's always best to do a hard refresh, command, shift r on Mac, ctrl shift r on PC).
8. Once you know it works, go ahead and just remove the old link.