Why won't my Office 365 Profile picture show in all of the Office 365 apps

If you updated your photo in one particular app, that may not be enough. Microsoft recommends that you use the profile link from Office.com. See this article from Microsoft about updating your photo:

https://support.microsoft.com/en-us/topic/add-your-profile-photo-to-microsoft-365-2eaf93fd-b3f1-43b9-9cdc-bdcd548435b7?ui=en-us&rs=en-us&ad=us

Note: It may take up to a few hours for your photo to appear in all apps, and you may have to log out and back in again to see the change.