Under 'Change your photo', select Upload a new photo, and then browse to find and choose the image file you want to use. Change your Microsoft account picture with a New picture you want and Save it.

In the window that opens, choose the picture icon ( Add or change your picture) to the left of your name.In the top right corner, select the picture icon ( Account manager).(Do not select anything on the sign-in pages other than Next and Sign in.) When prompted, confirm your identity with Two-Step Login (Duo), and then choose whether to stay signed into your Microsoft 365 account. If you see a 'Sign in' prompt, enter your IU username followed by (do this no matter what your email address is), and then, at the password prompt, enter your IU passphrase. Other users also may have to sign out and sign in again to see your new picture. To see your new picture in Microsoft Teams, you may need to sign out and then sign back in.After you modify your picture, it may take up to 24 hours for the change to appear in all applications.

How to change your microsoft account profile picture