You can be a member of more than one gym at the same time, or be a member at one and have a coach at another. The app lets you switch between them.
Where the switch is. At the top of the home screen, below the name of the app, is the gym you’re currently looking at. Tap it and you get a list of your gyms; choose one and the app switches over. The same choice is also under Profile, in Account.
It only appears if you have more than one. With one gym there’s nothing to choose, so nothing is shown.
What changes with it. The app’s colours and logo, your door code, the online shop and the challenges. Those belong to a specific gym, not to you.
What doesn’t change. Your workouts, your nutrition, your progress, your measurements and your photos. Those are stored under your account, not under a gym’s. That’s deliberate: if you switch gyms, you take your history with you.
Your choice is remembered on this device. On a second phone you set it separately -- handy if you want to see something different on the tablet at the gym than on your own device.