I've shot a video in vertical orientation for TikTok but when I edit in Vegas, the output does not fill my screen. I've been watching YouTube tutorials on this but can't figure this out. Attached is how rendered video looks when I play on my phone so you can see what I'm talking about.

I'm running Windows 10, on MSI GP76 Leopard, Vegas Pro 17.0 Platinum, 32.0 MB RAM, NVIDIA.

Thanks

Laurie