In AI Studio, open the settings and fill in the Brand Voice Kit:

• Brand name and Brand description: what you sell, for whom and why you're different;
• Target audience;
• Voice principles: for example "clear, friendly, practical, no hype";
• Preferred words / phrases;
• Writing examples: paste one to three texts that sound like you.

Under My defaults choose your default language and tone. All AI tools read these settings, so you don't repeat them every time.

In a team, only the workspace owner can change the shared brand voice.