1.) Start from your Core persona.
2.) Navigate to Users/Access > Profile > Edit User Profile Data.
3.) Search and select the user for which you want to update the User Photo.
4.) Scroll down to the lower left under System Information, and click User Photo.
5.) If there is currently no photo, click the Choose File button, and choose your photo.
6.) Enter a Caption (optional).
7.) Click Save or Save & Exit.

8.) If there is an existing profile photo you want to update, check the Delete on Save button.
9.) Click Save.
10.) Click the Choose File button, and choose your photo.
11.) Enter a Caption (optional).
12.) Click Save or Save & Exit.
Note: This can take 24 hours to display within some areas of the software

Also see: How do I bulk upload user photos?