When I export a video in FHD and upload it to YouTube, I can play it full screen with no problem but when I export the same video in 4k, even in full screen it doesn't fill up the entire screen. I can see that the same issue in the following video: https://www.youtube.com/watch?v=F4rojV54Rfk
But if you look at other 4k videos on the same YouTube channel (for instance, https://www.youtube.com/watch?v=bm8B8KTAHfg), they do go entirely full screen. Does anyone know if this is something that can be solved by changing my export settings? Any explanation for why the video doesn't fill up the entire screen when I upload a 4k video? I would appreciate any help.
I'm using h.264 4k when exporting and I shot the video in fhd.
Thank you for the response. I have tried UHD as it has the same ratio as fhd and it does fill up the entre screen but when I upload it to YouTube, the highest resolution for playback is 1080 p. Do you know in what format or resolution I have to export the video in PremierePro to make the option of 4k (2160p) available for playback on YouTube?