When your theme was installed, we installed some 'link lists' on your account. Link lists are the feature in your account that allow you to manage your site's menus.
If you want to change the links in these menus then you need to edit the link lists.
However you may have created new menus that you want to use instead (instead of editing an existing link list), in which case you'll need to assign the new link lists to your theme. To do so, follow the instructions below.
Go to the theme settings page (which can be accessed by clicking 'themes' from the left menu and then 'theme settings').
Scroll to the link lists section.
Your theme will have different places where it shows menus. Each of these places can have a link list assigned to it.
Choose the new link list from the drop down menu and then, when done, click the 'save changes' button at the bottom of the page.
You should then check your website to make sure that your menus are working correctly.