If you want to personalize your form or tailor it to your audience, you can add a theme to a form.
Add a theme or color
- Open a form in Google Forms.
- Click Style
.
- Choose a color for your form. Or, to add a theme, click Insert image
.
You’ll see your new theme and you can continue editing your form.
Upload an image as a theme
- Open a form in Google Forms.
- Click Style
.
- Click Insert image
.
- Click Upload photos.
- Drag a photo into the window or click Select a photo from your computer.
- Click Done.
Information found above comes from Google's Docs Editor Help page.