Zoom in or out on a photo: Click or drag the Zoom slider.
Make adjustments: Click Adjust to display the adjustment tools. See to have the color and contrast of your photo adjusted automatically. To remove the changes, press Command-Z or click Revert to Original.
To stop editing, click Done or press Return.
While you’re editing a photo, you can press the arrow keys to switch to other photos.
To create different versions of a photo, you duplicate it and work on the copy.
In the Photos app on your Mac, double-click a photo you’ve made adjustments to, then click Edit in the toolbar.
Choose Image > Copy Adjustments.
Double-click the photo to which you want to apply the adjustments, then click Edit.
Choose Image > Paste Adjustments.
Tip: You can also Control-click a photo and choose Copy Adjustments or Paste Adjustments.
Tip: You can quickly remove changes to a photo. To undo the last change you made, choose Edit > Undo, or press Command-Z. To discard all changes and start over, select the photo and choose Image > Revert to Original.