The Phone app on an iPhone allows you to create a list of frequently called phone numbers called Favorites. This allows you to quickly contact someone without having to search through your contacts.
To rearrange the order of your Favorites, go to the Phone app and tap the “Edit” button in the top left corner. After doing so, a screen with red icons to the left of the favorites and an icon with three lines will appear on the right column. Press and hold the icon with three lines next to the Favorite of your choice to rearrange the order of your Favorites. Move the selection up or down accordingly. When you’re done, press the “Done” button in the top left corner.