If you need to change the order of menu items in your Website's navigation, there is a simple way to do this in your Craft CMS.
Log in and navigate to 'Entries' and then to your website structure under 'Structures'.
You should be able to see a list of your parent pages and their child pages. To change the order of your pages, click this symbol and drag the item to where you'd like it to sit:
You will not need to use a 'Save' button - the change will occur immediately after you move the item.
Here is an example - the icon is to the left of the page.
After dragging the page to another location, pages are immediately re-ordered and this will be reflected on the live website.