Changing the Gmail theme on iPhone will include following the simple steps. Let’s check out the steps to know about how to change Gmail theme on iPhone device. From your Gmail app, you need to disable the existing Google suite account. From the app switcher, you need to close the application. Click to settings and then enable the dark mode on your iPhone device. Lastly, restart the Gmail app for changes to take effect. These are the steps that users need to follow to smoothly change Gmail theme on iPhone device.