HappyFox lets you add personalized logo and company name to your helpdesk account.
Navigate to the Main menu >> Account Settings >> Personalization (tab) 
Only account admin can perform these action. Agent marked under the Manage >> Account Settings >> Basic Settings >> Account administrator is the account admin of your account.
You can also choose to customize these for each of your brands by choosing "Customize Multi-Brand" option at the top right corner.