Preview stuck on mobile, can't switch to desktop

Hello,

I'm having an issue with Figma. I can only see the mobile preview, and I can't switch to a desktop preview (app neither web)

Also, when I watch tutorials, I see options like "Custom Settings", but these sections don't appear in my interface.

Because of that, I can't change the preview or configure it for desktop.

Does anyone know:

• why my preview is only in mobile view?

• how I can switch the preview to desktop?

• and why I don't have some options shown in tutorials (like "Custom Settings")?

Thanks in advance for your help!