To add your picture to your Office 365 profile, follow these steps:
1. Go to the Myapps dashboard and click on the profile icon in the top right corner and click on "View Account"
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2. Click on your initials or picture above your name and it will have you change your photo.
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3. Click on "Add a photo", go to the location of the photo you want to be added, and click Open. Once the photo replaces the current image, click Save.
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Your new profile picture should now be visible in Office 365. Note that it may take some time for the picture to propagate across all Office 365 services.