Your author name shows up in multiple places on wordpress. If it’s not quite how you like it then it’s quick and easy to change.
Click on your profile picture in the top admin menu then click Edit My Profile.
Scroll down until you see the Name section in the profile editor. What you put in the first name, last name and nickname textboxes will appear in the Display name publicly as dropdown in different variations.
Once you’ve filled out the textboxes choose an option from Display Name publicly as.
Scroll down to the bottom and click Update Profile.
Go to the homepage of your blog and you should see that your author name has been updated.