By J. D. BIERSDORFER

Q. After I crop and touch up a picture from my phone camera, I sometimes post the wrong one to my Facebook account because it’s hard to tell which version is which from the little preview images. Normally, I just delete the post with the wrong photo and upload the right one, but sometimes I don’t notice right away and people have already commented. Is there a way to replace the old picture with the new one without losing the comments?

A. As long as you have uploaded the photo directly (with Facebook’s own app for Android or iOS, for example) and not through a third-party program, you should be able to edit your post and swap in the photo you meant to use. To do that, go to the post on your Facebook timeline with the picture you want to change.

In the top-right corner of the post, tap the downward-pointing arrow icon and choose Edit Post from the menu. Tap the small “x” in the top-right corner of the photo (or photos) you want to remove, but do not click the Save button yet. Instead, tap the icon for adding photos down at the bottom of the screen.

Select “Photo/Video” from the menu. When your phone’s photo library opens, select the thumbnail of the photo you want to use and tap the Done button at the top. Once you have confirmed that this is the correct image, tap the Save button to update the post with the new picture.

You can use the Edit Post option to correct typos in previously published posts. In Edit mode, you can also go back and tag friends you missed the first time around or add the place the picture was taken if you did not have your phone’s Location Services setting enabled.