Adding Captions to Multiple Images in Multiple Posts
If you post a lot of photographs on your site, then perhaps you would like to revisit your photos and add captions to photos in different posts. You don’t need to open each post in the post editor just to add captions to images. You can add captions by editing an image directly.
To do that, go to Media » Library. There you will see all your photos and images. Take your mouse over to an image you want to edit, and you will notice that a few links would appear below it. You need to click on Edit Image link.
This will open image in the WordPress image editor screen. You can add caption to your image here. You can also crop, rotate, and resize your images from edit image screen.