If you are looking out for how to change Gmail theme then you need to start by signing in to the Gmail on web browser. After that, click on settings panel or gear icon and then choose themes. Here, different themes will appear and on scrolling below you will find the dark theme, native Gmail theme, and other presets. Users can also upload from my photos at the bottom. Here, you need to choose the desired theme or image and choose to save. After saving, you can enjoy using the changed Gmail theme.