To update the logo that will show in Office365 suite bar follow the steps below.
Navigate to Office365 Admin as shown below.
NOTE: You’ll need Admin Permissions to do that.
From the Admin Center, open the [Org settings] option (click image to enlarge)
From the Organizational Profile tab, click Custom themes and set the logo as shown in the screen sequence below (click image to enlarge).
- Click Save settings to save the new logo