Go to: My Account >> Edit User Details
You can use the logo/image that you may have already uploaded or click on the Image Library link to upload a new Image.
You can use this Company Logo on your Surveys, Email Invitation and also on Certain Reports. If you have an Organization account then the Main Account can upload and set up a Company Logo and this can be used across all Sub-Accounts. This will help users recognize / relate to your brand.
This feature is available with the following licenses :