In my opinion this is a trivial tutorial, but some people may find it difficult to change the profile picture on their blog, so I will make a replacement tutorial or change the admin profile photo on blogger.
At first glance it's hard we can't change it in the blogger settings section, because the blog profile has changed instead of using the Google+ profile again.
Some people who still use Google+ profiles may experience problems not being able to enter the blogger dashboard.
Therefore you need to change it to a blogger profile so you can access your blogspot dashboard page.
Back again, now we will change or change your blogger profile photo by using a URL or special link so you can edit the author's profile or blog admin profile, please read the tutorial until it's finished below:
How to Change Blogger Admin Profile Photos
1. Make sure you are logged in using your email.
2. Then open the following link:
https://www.blogger.com/edit-profile.g
3. Scroll down then in the Profile Photos section, please click Delete image.
4. Then select From your computer: then click Choose File. Or you can choose from the web. Paste the image URL below. Here I use photos from a computer.
6. If it has been uploaded, please scroll down again then click Save Profile.
Conclusion
Before Google+ was deactivated, you can change or change your blog profile photo via a Google+ profile because some people will definitely use Google+ profiles on their blogs and not blogger profiles.
For now all blogspot users are required to use blogger profiles to be able to use this blogger service.
And to change the blogger profile photo there is a way that you can see in the tutorial above, you must visit the link or special URL to be able to edit or change information about your blogger profile.
