Customized emblems have been a feature included in Halo online multiplayer since the early days of the series. It’s never been a deep customization system, but it allows players to stand out from the crowd with a different symbol compared to the others. Lots of people in the early Test Flights of Halo Infinite are wondering how to change their emblem, but the answer will be disappointing.
As of the second Halo Infinite Test Flight, there is no way to change your emblem. In the full release, you will be able to access this area by going to the Customize tab on the main menu and opening Spartan ID. During the Test Flight, the option is grayed out.
In the first Test Flight, players were able to customize their emblems by downloading the Halo Waypoint app, but it is currently unavailable. Back then, there was a Test Flight for the app that will be released alongside Halo Infinite, but it is currently not in a public test, so there is no way to access that portion of the game.
It may be a little disappointing not to be able to set more customization features during the testing of Halo Infinite, but at the end of the day, this period is mostly meant for finding gameplay areas that the game is broken and reporting it to the developers. If the Spartan ID section is not quite finished yet, it should be in line for when the game releases.