Just follow these simple steps.
OpenPhotoson your iOS equipment.
Tap the Live Photo you want to edit.

This process only works on Live Photos.
TapEditin the upper right corner to open Photos' editing functions.
Tap thewhite box, and iOS will display a small white dot.

This references where on the timeline your current Key Frame is located.
Touch and hold the white box to slide it left and right along the timeline.
As you move, you will see the main image change.

This is a preview of your frames.
The faster you move, the quicker the image scrubs.
Move the white box slowly to find the perfect moment.

Once you’ve found the right frame, lift your finger.
TapMake Key Phototo set the frame as your new main image.
You will now see two white dots on the timeline.

The first dot (slightly dulled out) references your starting frame.
The second dot (just above the white box) is the new Key Frame.
If you want to pick a new frame, repeat steps 5 to 7.

To compare your new frame with the original one, move the slider to the first white dot.
Double-nudge the Live Photo you want to work with to open it.
SelectEditin the upper right corner to pop swing open the editing functions.

Select thewhite box, and slide it left or right to choose a new Key Frame.
As you move, you will see the main image change.
Move the box slowly to find the perfect moment for your shot.

Once you’ve chosen your frame, selectMake Key Phototo set the frame as your new main image.
You will now see two dots above your timeline.
The slightly dulled out dot refers to the original frame and the second references the new Key Frame.

Once you’re happy with your selection, pressDonein the upper right corner.
You’ve selected a new frame for your Live Photo.
FAQ
Totake a live photo, initiate the iPhone’sCameraapp.
In the upper-right corner of the screen, find thethree concentric circlesand verify it’s turned on.
Take your photo as you normally would.
You canmake a live photo into a videousing theGoogle Photosapp.
Choose the live photo you want to work with > select thethree-dots>Save as video.