Follow the below steps to change the default USD logo.
Step 1: Open Dynamics CRM (Online or On-Premise). Navigate to Settings -> Customizations and click on Customize the System.
Step 2: Click on Web resources and open the msdyusd_Logo web resource.
Step 3: Choose File and upload the required PNG format file. Save and Publish the Web resource.
Launch the Unified Service Desk Client to see the changes.
Note: Created the custom Microsoft logo with the 465 x 68 Dimensions.