How to configure global theme and logo in Microsoft 365

The Microsoft 365 application bar is a user interface element that provides access to various applications and features in the Microsoft 365 ecosystem.

It typically appears at the top of the screen and can be used to navigate between applications such as Outlook, Word, Excel, and PowerPoint, as well as to access other features like OneDrive, SharePoint, and Teams. The application bar is designed to make it easy for users to access the tools they need to get their work done, and to quickly switch between different applications and tasks.

https://learn.microsoft.com/en-us/microsoft-365/troubleshoot/installation/blank-app-launcher-and-menu-bar