How to retain original publishing date of an edited article in blogger?

No, I don't think after saving your changes, it can retain the original publishing date. Even after reverting to draft an then republishing, it shows the same date, that is, the updated one.

In this case, if my article was copied by some one else and he or she updates the date before my original publication date, how Goolge look at it when I file DMCA complaint regarding this? Does it mean that I have COPIED the article from who actually copied my article?

There is no way which can help you in restoration of your original publishing date. The only thing you can do is to revise the article completely before submission.

Well, yes in the case if your article was copied by some one else and he or she updates the date before your original publication date you may be the victim.

The best way to get rid of this is to make your article a bit private, also i suggest you that whenever you write any article write it directly on your blog don't store it somewhere else.

You can change the post date after saving your post on blogger. For changing the publish date, you need to follow the below steps:

1. First go to Posts on your main Blogger screen.
2. Click on Edit of your post.
3. At the bottom left, click Post Settings.
4. Go over to Published On.
5. Click Post Date and Time.
6. Change the date to whatever you would like.
7. Click Update and you're done.

Hope this was helpful to you.

Well, one must agree it is absolutely necesssary to keep your old posts updated. In addition to updating the content of the post, if you want to retain the old post date, here is how you can do it.

1. Log in to your blogger account.

2. Now navigate to the site concerned ( if you have more than one sites) and click on Posts.

3. You will get a list of articles posted on the site. Select the post desired. If the list is quite longer, you may use the search function to locate the post.

4. Hovering the cursor on post title will provide a link to Edit Post.

5. You will be taken to Post Editor. Make necessary changes to the post.

6. Now navigate to Post Settings which you can locate at bottom left.

7. Locate Published On ->Set Date and Time.

8. Click on the required date on the calendar widget that appears.

9. Click on Done once you have finished setting the date.

10. Now click on Update button at the top of the screen.

That's it - you have successfully changed the date of your post.