By Ken Burkhalter updated on 04/04/2016
The iPhone's Menu Bar at the bottom of the screen provides a means to access the most common applications across all Home Screens. While Apple's default choice of apps may be just fine for you, if you ever want different options then you can switch out the icons to meet your needs.
To exchange one of your Home Screen icons with an existing Menu Bar icon, just tap and hold on a Menu Bar icon until the icon begins to shake. Then drag/drop the Menu Bar icon you want to remove from the Bar to the Home Screen. This leaves three icons on the Bar.
Next, drag/drop the Home Screen icon you want onto the Menu Bar and position it in any of the four slots.
Repeat this for any other icons you wish to change. When done, tap the Home Button to exit shimmy/shake mode.